Modern Concept Science and Environment - 7 243
FACT WITH REASON
Igneous rocks are called granular rocks, why?
Igneous rocks are called granular rocks because it contains granules formed during rapid
crystallization of magma.
Types of Igneous Rocks MEMORY PLUS
Based on the mode of formation, igneous rocks There are over 700 different kinds
are of two types. They are: plutonic rocks and of igneous rocks that have been
volcanic rocks. identified.
a) Plutonic rocks
The high pressure in the mantle region of the earth forces magma to rise into
the earth’s crust. During this event, magma gradually solidifies in the earth’s
crust and forms rocks. Such types of igneous rocks that are formed by gradual
solidification of magma below the earth’s surface are called plutonic rocks.
Plutonic rocks are also known as intrusive rocks. Diorite, gabbro, granite,
pegmatite, peridotite, etc. are the examples of intrusive igneous rocks. As
plutonic rocks are cooled slowly down below the crust, they have large crystals.
These rocks are hardest rocks and have high strength.
Gabbro Granite Peridiotite Dunite
FACT WITH REASON
Plutonic rocks do not have fossils, why?
Plutonic rocks do not have fossils because it is formed when hot magma solidifies. So any
plant parts will be burnt away.
b) Volcanic rocks
Sometimes magma erupts out in the earth’s surface from the cracks, fissures
and weak spots of the earth crust. Magma that erupts out in the earth surface
as a volcano is called lava. Lava solidifies to form igneous rocks. Igneous rocks
formed after the solidification of lava are called volcanic rocks. They are also
known as extrusive igneous rocks. Examples of extrusive igneous rocks are:
244 Structure of the Earth
andesite, basalt, obsidian, pumice, rhyolite, scoria, etc. As volcanic rocks are
formed by rapid cooling of lava, they have small crystals in them. They can also
be porous and glassy. These rocks have low strength.
Basalt Pumice Obsidian
Differences between magma and lava are:
S.N. Magma S.N. lava
1 The molten material present inside 1 The molten material that pours out
the earth is called magma. from a volcano is called lava.
2 Magma solidifies into plutonic 2 Lava solidifies into volcanic rock.
rock.
Some Important Igneous Rocks Granite MEMORY PLUS
Granite has been used for thousands
a) Granite of years, as building material,
bridges, paving, monuments,
Granite is a coarse-grained granite slabs, tiles and many other
plutonic igneous rock with places.
visible crystalline formation. It
mainly contains minerals like
quartz, feldspar and mica. Granite is usually white or grey with a speckled appearance
caused by the darker crystals. Granite has greater strength than sandstone, limestone,
and marble. It is an important building material.
FACT WITH REASON
Granite is igneous rock. Why?
Granite is igneous rock because it is formed by solidification of magma.
b) Pegmatite Pegmatite
Pegmatite is a light-coloured and coarse-grained plutonic
igneous rock. It often contains rare minerals like boron,
beryllium and lithium that are not found in other parts of
the magma chamber.
Modern Concept Science and Environment - 7 245
c) Obsidian MEMORY PLUS
Obsidian is a volcanic rock Obsidian is also known as
that forms from the very rapid "nature's glass" because of its
cooling of molten rock material. glassy appearance.
It cools so rapidly that there is
no formation of crystals. Obsidian is usually black, red or Obsidian
brown. Obsidian is a glassy igneous rock.
FACT WITH REASON
Obsidian is an extrusive rock but granite is an intrusive rock.
Obsidian is an extrusive rock because it is formed by the solidification of lava outside the
earth’s crust. But, granite is an intrusive rock because it is formed by the solidification of
magma inside the earth’s crust.
d) Pumice
Pumice is a very light and MEMORY PLUS
porous volcanic igneous Ninety-five percent of the Earth's
rock having a spongy crust is made of igneous rock.
texture. It is composed largely of glass. It forms through
very rapid solidification of lava. A form of fine grained Pumice
pumice is used in cement.
Differences between sedimentary rock and igneous rock are:
S.N. Sedimentary rock S.N. Igneous rock
1 Rocks that are formed by the 1 Rocks that are formed by the
accumulation and cementing of solidification of magma are called
deposited sediments are called igneous rocks.
sedimentary rocks.
2 Sedimentary rocks may contain 2 Igneous rock do not contain
fossil. Example: limestone fossil. Example: pumice
3. Metamorphic rocks
The word metamorphic is derived from the Greek words: ‘Meta’ means ‘change’
and ‘morph’ means ‘to form’. In nature, the sedimentary or igneous rocks buried
deep below the earth’s surface are exposed to various extreme conditions like high
temperature, pressure and chemical changes. These conditions alter the texture,
minerals and chemical composition of the rocks. Such types of rocks that are formed
by the modification of pre-existing rocks as a result of heat, pressure and chemical
processes are called metamorphic rocks. There are two basic types of metamorphic
rocks: Foliated and Non-foliated metamorphic rocks.
246 Structure of the Earth
a) Foliated metamorphic rocks
The metamorphic rocks that have a layered or banded appearance are called
foliated rocks. These bands are produced as a result of exposure to heat and
pressure. Examples are: gneiss, phyllite, schist, and slate.
FACT WITH REASON
Gneiss is known as foliated rock, why?
Gneiss is known as foliated rock because it has a layered or banded appearance.
b) Non-foliated metamorphic rocks
The metamorphic rocks that do not have layered or banded appearance
are called non-foliated rocks. Examples are: hornfels, marble, quartzite,
diamond and novaculite.
Marble Slate Quartzite
Gneiss Schist Phyllite
The chart below is of some of the metamorphosed forms of pre-existing rocks.
Sedimentary Rocks Metamorphic rocks
Limestone Marble
Dolomite Marble
Coal Graphite
Igneous Rocks
Granite Gneiss
Diorite Schist
Metamorphic Rocks
Graphite Diamond
Modern Concept Science and Environment - 7 247
The process of modification of sedimentary, igneous or metamorphic rocks is called
metamorphism. Usually metamorphism occurs due MEMORY PLUS
to processes like mountain building, tectonic activity, Metamorphic rocks are so called
etc. Immense pressure to pre-existing rocks due to because they always begin as
these processes deforms rocks and compacts them another type of rock.
into small volumes and high density.
Uses of rocks
There are many uses of rocks. Some of the most common uses are given below:
a) Construction materials
Rocks are used as building materials for the construction of buildings, roads,
dams and other development works. Granite, shale, marble, limestone,
sandstone, slate, etc. are widely used for construction.
b) Decorative materials
Rocks or mineral aggregate are used in making statues, idols, etc. Marble is
widely used to decorate floor and walls in building. Slate is used to decorate
steps, walls and roofs. Quartz is used to extract silica.
c) Extraction of minerals
Rocks are the source of extraction of large industrial minerals. Minerals like
iron, phosphorous, magnesium, calcium carbonate, etc. are widely used in many
industries. For example: limestone is used to extract calcium carbonate.
d) Jewelleries
Minerals like diamond, ruby, gems, quartz, MEMORY PLUS
etc. are used in jewelleries. Diamond is the hardest mineral.
e) Cosmetics
Minerals like talcum powder is used as a source material for the production of
cosmetic items like talcum powder.
f) Study purposes
Fossils in the sedimentary rocks help in the study of evolution of living beings.
Similarly, igneous rocks provide information about the composition of earth’s
interior.
19.2 Rocks Found in Nepal
Nepal is a mountainous country with rocky terrain. Hence, there is a large deposit
of different types of rocks. All three major types of rocks are found in Nepal as its
geological history had sedimentation, volcanism and metamorphism. Some of the
common rocks found in Nepal are discussed below:
248 Structure of the Earth
a) Conglomerate
Conglomerate is a coarse grained sedimentary rock formed by the aggregation of
rocks fragments. These rock fragments are held together by cementing materials
like clay. It is a low quality rock as it has low strength. It is a common rock of
Nepal and is found in the rivers.
b) Sandstone MEMORY PLUS
Like conglomerate, sandstone is also a It takes thousands of years to form
sedimentary rock formed by binding of sand sandstone.
particles. Sand particles are bound by mineral cement. It is a low quality rock as
it has low strength. In Nepal, sandstone is usually found in flood plain. It is used
as building material mainly for flooring and pavements.
c) Silica
Silica itself is actually not a rock but a mineral compound formed from silicon and
oxygen. High quality silica is present in a place called Karrakhola in Makwanpur
district of Nepal. Silica is an important material used in the manufacture of
cement and glass.
d) Limestone
Limestone is a sedimentary rock formed by the accumulation of mineral called
calcium carbonate. It is one of the most extracted minerals of Nepal used for
the manufacture of cement. Nepal has large deposits of limestone. Places like
Godavari (Lalitpur), Bhainse (Makwanpur), Jogimara (Dhading), Sindhali
(Udaypur), Kakarukhola (Sindhuli), Gandari (Dang), etc. have deposits of
limestone.
e) Marble
Marble is a high quality metamorphic rock. It is widely used in construction
purposes especially in indoor decoration in staircase, toilets, room floors, etc.
Some of the common deposits of marble in Nepal are in Godavari (Lalitpur),
Anekot (Kavre) and ChhatreDeurali (Dhading).
f) Slate MEMORY PLUS
Slate is used for different varieties of
Slate is a fine grained metamorphic rock flooring and roofing.
formed by metamorphosis of mudstone or
shale. Deposits of slate are present in many districts of Nepal among which
Tanahun, Nuwakot, Sindhupalchok, Dhadhing, Baglung, Parbat, Jajarkot,
Accham, Doti, Dadeldhura, etc. are some few.
Modern Concept Science and Environment - 7 249
FACT WITH REASON
Slate is a metamorphic rock, why?
Slate is a metamorphic rock because it is formed by changing sedimentary rock.
STEPS EXERCISE
STEP 1
1. Fill in the blanks with appropriate words:
a) The eroded fine materials resulting from the weathering of rocks are called
………..
b) The mixture of molten rocks and minerals is called ……………..
c) Granite is a coarse-grained …… rock with visible crystalline formation.
d) The process of modification of sedimentary, igneous or metamorphic
rocks is called …….
e) …………. district of Nepal is famous for the deposits of high quality silica.
2. Write ‘True’ for the correct and ‘False’ for the incorrect statements:
a) Texture means the colour of minerals in its powdered form.
b) Sandstone is a sedimentary rock.
c) Intrusive igneous rocks are formed from lava.
d) Marble is a foliated metamorphic rock.
e) Talc is a mineral used in cosmetic products.
3. Match the following: i) Basalt
a) Cleavage ii) Layer of breaking surface
b) Non-foliated metamorphic rock iii) Quartzite
c) Rock with fossil iv) Sandstone
d) Sedimentary rock v) Shaligram
e) Extrusive rock
STEP 2
4. Answer the following questions in one word:
a) Name the hardest mineral.
b) Write the name of one mineral deposit found in Godavari (Lalitpur) of
Nepal.
c) What is the term used for hard solid substance made of one or more
minerals?
250 Structure of the Earth
d) What type of rock is pumice?
e) What is the plane through which the rock or a mineral in the rock breaks out?
5. Write any two differences between:
a) Sedimentary rocks and igneous rocks
b) Igneous rocks and metamorphic rocks
c) Extrusive and intrusive rocks
d) Foliated and non-foliated rocks
e) Marble and conglomerate
f) Magma and lava
6. Give reasons:
a) Sedimentary rocks may have fossils in them.
b) Igneous rocks are called granular rocks.
c) Metamorphic rocks have high density and low volume.
d) Obsidian is an extrusive rock but granite is an intrusive rock.
e) Gneiss is known as a foliated rock.
7. Name the rocks shown in the following figure:
a) b) c) d) e) f)
STEP 3
8. Answer the following questions:
a) What is a rock? List any four important uses of rocks.
b) How is soil formed?
c) What is sedimentary rock? How are sedimentary rocks formed?
d) Define igneous rock. Explain how plutonic rocks are formed.
e) What are volcanic rocks? List any three examples.
f) Describe the process of formation of metamorphic rocks.
g) Define mineral. Name any four major rocks/minerals of Nepal with the
name of place they are commonly found.
9. Give at least two examples of the following:
a) Intrusive rock b) Extrusive rock
c) Foliated metamorphic rocks d) Non-foliated metamorphic rocks
UNIT Estimated teaching periods TheoMryoderPnraCcotniccaepl t Science and Environment - 7 251
51
20
Weather and Climate
Syllabus issued by CDC Cloud
Introduction to weather and climate
Cloud, rain, snow, dew drops
Atmosphere and its layers
Wind and movement of air
Weather forecasting and equipment for measuring factors affecting weather
LEARNING OBJECTIVES
At the end of this unit, students will be able to:
introduce cloud, rain, snow and dew drops.
introduce atmosphere and describe the various layers of atmosphere.
explain the causes and effects of movement of air.
describe the methods of weather forecasting and forecast local weather.
introduce the equipment for measuring the factors of weather.
Key terms and terminologies of the unit
1. Weather: Weather is a condition of atmosphere of a place at a particular time.
2. Climate: Climate is defined as the average weather condition of a region over a
period of several years.
3. Cloud: Clouds are the white or grey visible floating mass of water and/or ice
particles in the atmosphere.
4. Rain: Rain is condensed form of water vapour that falls down from clouds as
water droplets.
5. Snow: Snow is a transparent ice crystal formed around small particulates in
the atmosphere that falls towards the earth surface.
6. Dew: Dew is the tiny drops of water that is formed by condensed water
vapour over the surface of outdoor objects during cold nights.
7. Air: Air is a mixture of different gases that composes the atmosphere of the
earth.
8. Atmosphere: The layer of air that surrounds the earth is called atmosphere.
252 Weather and Climate
9. Troposphere: Troposphere is the lowest layer of the earth’s atmosphere where
weather phenomena occur.
10. Stratosphere: Stratosphere is the layer of the atmosphere between troposphere
and mesosphere.
11. Mesosphere: Mesosphere is the atmospheric layer above stratosphere and
below thermosphere and lies from 50 to 80 km vertically above
the earth.
12. Thermosphere: Thermosphere is the hot layer of atmosphere which lies above
mesosphere and below exosphere.
13. Exosphere: Exosphere is the uppermost layer of atmosphere which extends
from 720 km to 16,000 km above the earth.
14. Wind: Wind is the air in motion in relatively higher speed.
15. Convection: The process of transfer of heat energy by the movement of air
molecules is called convection.
16. Breeze: Smoothly moving air is called breeze.
17. Sea breeze: The wind that originates from high pressure area at sea and
blows towards low pressure area at land during the day is
called sea breeze.
18. Land breeze: The wind that originates from high pressure area at land and
blows towards low pressure area in the sea during night time is
called land breeze.
19. Ozone: Ozone is a gas which contains three atoms of oxygen.
20. Weather forecasting: Prediction of the upcoming weather or weather events with
the help of past and existing atmospheric conditions is called
weather forecasting.
21. Humidity: Humidity is the measure of the amount of moisture in the air.
22. Thermometer: A thermometer is an instrument used to measure temperature.
23. Relative humidity: Relative humidity is the percentage of water vapour present in
the air out of the total water vapour holding capacity of the air
at that temperature.
24. Hygrometer: A hygrometer is an instrument used to measure relative
humidity.
26. Anemometer: An anemometer is a type of weather instrument that measures
wind speed.
Modern Concept Science and Environment - 7 253
27. Rain gauge: A rain gauge is an instrument used to measure the amount of
28. Barometer: liquid precipitated over a certain duration of time.
Abarometer is a device used to measure atmospheric pressure.
20.1 Introduction
Are all days sunny? Of course not. Some days are MEMORY PLUS
windy, some are rainy, some are cold and some are On 14th April, 1986, Bangladesh was
hot. We experience change in hotness, coldness and hit by the biggest hailstones ever
rain in different months, days or even hours. Weather recorded. The weighing in at over
is a condition of atmosphere of a place at a particular 1kg each that killed 92 people.
time. Sunlight, wind, clouds, rain, etc. are the major
elements of weather that cause change in atmospheric MEMORY PLUS
condition of a place. As weather of a place depends The Earth’s atmosphere carries about
upon different weather elements, it can change in 1800 thunderstorms at any given time.
every hour or days or remain same for months.
FACT WITH REASON
Sunlight is the most important component of weather.
Sunlight is called the most important component of weather because the amount of sunlight
highly influences temperature, humidity, etc.
Climate is defined as the average weather condition of a region over a period of several
years. For example: the climate of mountain region of Nepal is cold. It is because it has
cold weather for most of the time in a year and this occurs regularly. Similarly, the
Terai region of Nepal has hot climate and hilly region has mild climate.
Differences between weather and climate are:
S.N. Weather S.N. Climate
1 Weather is a condition of 1 Climate is defined as the average
atmosphere of a place at a weather of a region over a period of
particular time. several years.
2 Weather covers a small area. 2 Climate covers a vast area.
20.2 Different Forms of Water
Water is not the component of weather but it exists in different forms that are
responsible for changing weather of a place. Some of these forms are discussed below.
254 Weather and Climate
Clouds
Clouds are the white MEMORY PLUS
or grey visible floating
mass of water and/ Cumulonimbus clouds can up to half a
million tons of water at one time.
or ice particles in the
atmosphere. The sunlight heats the water bodies like
lakes, seas, oceans, etc. and evaporate water from their
surface, in the form of water vapour. Water vapour rises Cloud
up and condenses to form clouds. Very fine dust particles called condensation nuclei
hold water vapour in them and helps them to condense into water droplets and or ice
particles. Cirrus, cumulus, stratus and nimbus are the major types of cloud. Different
clouds have different colour, shape, size, water holding capacity and the altitude.
Clouds form at an altitude of about 1.5 km to 16 km.
Rain
Rain is the condensed MEMORY PLUS
form of water vapour Hail, sleet, and snow are all
that falls down alternative forms of rain.
from clouds as water droplets. Large and continuous
accumulation of water in the clouds makes clouds
heavier. When clouds cannot hold water anymore, the Rain
water in them leaks in the form of rain. Nepal receives orographic rainfall. Orographic
rainfall occurs when clouds are cooled rapidly into water droplets when the clouds
strike hills and mountains. Nepal receives more than 80% of its total rainfall during
June to September.
Snow
Snow is a transparent ice MEMORY PLUS
crystal formed around The world's largest snowflake was
small particulates in recorded in the Guinness Book of
the atmosphere that World Records, at 38 cm wide and
falls towards the earth’s 20 cm thick. The snow flake fell at
surface. Partly melted Fort Keogh, Montana, USA on 28th
January, 1887.
crystals usually cling together to form snowflakes. Snow Snow
forms when the water vapour condenses at the temperature below the freezing point
of water. Snowfall is common in winter in Himalayan region of our country. Higher
Himalayas of Nepal are permanently covered by snow.
Modern Concept Science and Environment - 7 255
FACT WITH REASON
Snowfall is common in winter in Himalayan region of Nepal. Why?
Snowfall is common in winter in Himalayan region of Nepal because Himalayan region is at
high altitude and very cold. so rain changes into snow.
Dew
Dew is the tiny drop of water that is formed by the MEMORY PLUS
condensed water vapour over the surface of outdoor When the temperature is very low,
objects during cold nights. During cold night, the air dew changes to form ice. This form
temperature drops below and the excess moisture is called frost.
present in the cold air get condensed into tiny droplets of water. That is why, dew is
seen over the grass, plant leaves and other outdoor objects during winter morning.
Dew increases if the days are warmer and the nights are colder.
The temperature at which air condenses to form dew is called dew point. If the dew
point is below the freezing temperature of water, frost forms. Frost is the crystal of
frozen water deposited on cold surface of outdoor objects.
Dew Frost
FACT WITH REASON
Why do we see dew in winter season?
We see dew in winter season because water vapour of air changes into dew due to coldness.
ACTIVITY 1
Take a glass of water at room temperature and cover it by a plate. Take another glass of
water with ice crystals in them and cover it. Leave both glasses for about 10 minutes.
You will see the droplets of water outside the glass with cold water in it. These droplets
are dews. There will be no dews outside the glass with water at room temperature.
This is because water vapour in the air gets condensed when it comes in contact with
the cold glass surface.
256 Weather and Climate
20.3 Air
Air is a mixture of different gases that composes the atmosphere of the earth. The
main constituents of the atmosphere of Earth are nitrogen (78 %) and oxygen (21%),
argon (0.9%), carbon dioxide (0.03 %), varying amounts of water vapour and trace
amounts of hydrogen, ozone, methane, carbon monoxide, helium, neon, krypton,
xenon etc. Air also contains tiny airborne particles.
FACT WITH REASON
Why does air move?
Air moves due to differences in temperature and pressure of air in different places.
20.4 Atmosphere
Our earth is surrounded by different layers of air that differ from each other in
density and composition of gases. The layer of air that surrounds the earth is called
atmosphere. The atmospheric pressure decreases when the altitude increases. Our
atmosphere is divided into five different layers. They are troposphere, stratosphere,
mesosphere, thermosphere and exosphere.
MEMORY PLUS
Atmosphere exists due to the gravity
of the earth.
MEMORY PLUS
The troposphere contains
approximately 99% of the water vapour
in the earth's entire atmosphere.
Layers of atmosphere
Troposphere
Troposphere is the lowest layer of the earth’s atmosphere which extends up to the
altitude of 16km from equator and 8 km from the poles. It is the site of all-weather
events like rainfall, snowfall, hurricane, cyclones, etc. on the earth. The end of the
troposphere is called the tropopause. Tropopause separates the troposphere from the
stratosphere. Temperature in the troposphere decreases with height. It contains 75 %
of the atmosphere’s mass. The gases present in the troposphere are: nitrogen, oxygen,
argon, carbon dioxide, water vapour and traces of hydrogen, ozone, methane, and
other constituents.
Modern Concept Science and Environment - 7 257
FACT WITH REASON
Troposphere is important for weather forecasting. Why?
Troposphere is important for weather forecasting because all of weather related activities
occur in troposphere.
Stratosphere
Stratosphere is a layer of the atmosphere between MEMORY PLUS
troposphere and mesosphere. It starts at an altitude The uppermost part of the
of 8 km at poles and 16 km at the equator. It extends stratosphere is called stratopause.
up to an altitude of 50 km. Ozone gas is one of the
Airplanes fly in the stratosphere.
most important gases of stratosphere. Ozone absorbs different ultraviolet (UV) rays
from the sun and protects numerous life forms on the earth. UV rays can destroy living
beings by damaging their cell structure. Temperature decreases in lower portion of
stratosphere and increases in the upper portion due to the absorption of sunlight by
ozone. Stratopause separates stratosphere from mesosphere.
FACT WITH REASON
Ozone is known as the protective blanket of the earth.
Ozone is known as the protective blanket of the earth because it protects us from harmful
solar radiation.
Differences between troposphere and stratosphere are:
S.N. Troposphere S.N. Stratosphere
1 Troposphere is the lowest layer of 1 Stratosphere is layer of the
the earth's atmosphere. atmosphere between troposphere
and mesosphere.
2 The constituent gases are: 2 The gases present in stratosphere
nitrogen, oxygen, argon, carbon are ozone, oxygen and nitrogen.
dioxide and water vapour.
Mesosphere
Mesosphere is the atmospheric layer above MEMORY PLUS
stratosphere and below thermosphere. It extends The mesosphere is the coldest
from 50 km to 80 km, vertically above the earth. In atmospheric layer surrounding
this layer, temperature decreases with increase in the earth. It becomes cold enough
altitude. The top of the mesosphere is the coldest to freeze water vapour in its
part of Earth’s atmosphere. Most meteors from space atmosphere into ice clouds.
burn up in this layer. Mesopause separates mesosphere from thermosphere.
258 Weather and Climate
FACT WITH REASON
Mesosphere is the coldest layer of air. Why?
Mesosphere is coldest layer because cold wind blows in it all over the year.
Thermosphere
Thermosphere begins at an altitude of 80 km and MEMORY PLUS
extends up to 720 km vertically above the earth. Ionosphere is a place where most of our
This layer is called thermosphere due to its high satellites, including the International
Space Station are parked.
temperature which reaches to about 1200°C. Due to
high temperature, the air molecules in this layer are ionized. The ionized layer,also
known as ionosphere.
Exosphere MEMORY PLUS
Exosphere is the uppermost layer of the atmosphere The exosphere extends into a black or
which extends from 720 km and above. It has no or dark blue region beyond the earth. While
very few amount of air. Temperature is very high in the mesosphere is dark blue and closer
this layer due to its closeness to the sun. to the earth. They are the cloudy areas of
the stratosphere and troposphere.
20.5 Wind
Fast blowing air is called wind. Wind blows because
air moves from one place of the earth to another
due to the differences in pressures. The two main
causes of blowing of wind are unequal distribution
of heat energy from the sun and force of rotation of
the earth. Radiation from the sun heats up the land
surface. The air just above this surface also becomes
hot. The heat forces the air molecules to spread and Wind
rise up until the temperature of this air becomes
same with the surrounding. The process of transfer of heat energy by the movement
of air molecules is called convection. Rising of hot air creates empty spaces on the land
with decreased air pressure. This difference in air pressure forces the cold air to blow
quickly and occupy the empty space in the form of wind. Such convection of hot and
cold air masses results in the blowing of wind.
Strong winds are called storms. They can blow away roofs, clothes, uproot trees, etc.
and can harm people. Wind and storms are common in Nepal during March and April.
Modern Concept Science and Environment - 7 259
Movement of air
Slow and smooth moving air is called breeze. It arises due to unequal distribution of
heat between the land and the ocean. Based on the direction of moving air, breeze are
of two kinds: sea breeze and land breeze.
During the day, the sun heats up both the ocean Warm air
surface and the land. But, the land gets heated
faster than the water. The hot air above the land Cold sea breeze
rises up quickly and forms a low pressure region
on the land surface. Then, the air at higher pressure
above the water blows towards the land surface to day land warmer Sea cooler
fill up the gap. Thus, the sea breeze occurs. Sea breeze
FACT WITH REASON
The temperature of the coastal areas is almost moderate. Why?
Due to sea breeze during day and land breeze in night, the temperature of the coastal areas
is almost moderate.
During the night, the reverse occurs. The water
cools down slower than the land. Thus, it is at a warm air
higher temperature than the land surface. So, the Cool
air above the water rises up and creates a low land breeze
pressure region. To fill in the gap, the air blows
from the land towards the sea side. Thus, land
breeze occurs. night land cooler Sea warmer
Land breeze
20.6 Information Regarding Weather
Radio and television broadcast weather information of past, current and future for
that day. Newspaper also publish information of weather like the time of sunrise,
sunset, variation in temperature, relative humidity, etc. This information is provided
to the media by meteorologists. Meteorologists study weather and interpret weather
information by analyzing status of weather elements. Status of weather elements are
obtained from various instruments of meteorological stations. Information regarding
the weather helps people to plan their daily events.
20.7 Weather Instruments
Weather instruments are used to take measurements of temperature, wind, humidity,
rainfall and other atmospheric factors. They provide information about the weather
and climate of a place.
260 Weather and Climate
Thermometer
A thermometer is an instrument used to measure temperature.
Most thermometers measure air temperature by direct contact
with the air. The thermometer that is used in weather stations
to measure the maximum and minimum temperatures of the
day is maximum-minimum thermometer. Maximum-minimum
thermometer measures the maximum and minimum temperature
within the duration of 24 hours at a particular place. Nowadays, Maximum-minimum
temperature is recorded by an electronic temperature sensor.
thermometer
Anemometer
An anemometer is a type of weather MEMORY PLUS
instrument that measures wind speed. Anemometers are extremely
Some of these instruments measure important at airports where wind
both wind speed and wind direction. data is vital for safety.
A windmill anemometer is a common instrument used at weather
stations to obtain the wind speed. A wind vane is used as a part of the
anemometer to determine the direction of the wind. As the wind flows Anemometer
over the windmill, the speed and direction of the wind can be measured with this
instrument.
FACT WITH REASON
Why is anemometer called a weather instrument?
Anemometer is a weather instrument because it helps to measure wind speed and predict weather.
Hygrometer MEMORY PLUS
A hygrometer is an instrument Hygrometers are used in
used to measure relative greenhouses to regulate the
humidity. Humidity is the moisture content in the atmosphere
measure of the amount of which can affect plant growth.
moisture in the air. Relative humidity is the percentage of water
vapour present in the air out of the total water vapour holding
capacity of the air at that temperature. A sling psychrometer is a Hygrometer
common instrument used by meteorologists to determine the relative humidity.
FACT WITH REASON
Why is hygrometer called a weather instrument?
Hygrometer is a weather instrument because it measures humidity which helps to predict
weather.
Modern Concept Science and Environment - 7 261
Rain Guaze
A rain gauze is an instrument used to measure the amount Rain guaze
of liquid precipitated over a certain duration of time. In
its simplest sense, a rain guaze is a can which collects rain
water and measures its volume. The depth of the rain
can be measured with a ruler usually in millimetre (mm).
Rain guaze are placed in open areas where there are no
obstructions.
Barometer
Atmospheric pressure MEMORY PLUS
is measured by Mercury barometer was invented by
barometers. There are an Italian Scientist E. Torricellie.
different kinds of barometers. Some of them are mercury
barometer, aneroid barometer and digital barometer.
The standard atmospheric pressure shown by mercury
barometer at sea-level at 00C is 760mm of Hg. Nowadays,
aneroid barometer is commonly used as they do not Barometer
contain mercury and are highly portable. An aneroid
barometer uses a sealed can of air to detect changes in atmospheric pressure.
20.8 Weather Forecasting
Prediction of the upcoming weather or weather events with the help of past and
existing atmospheric conditions is called weather forecasting. Meteorologists analyze
data of past and present weather elements and MEMORY PLUS
forecast the upcoming weather situations. Troposphere is very important
Nowadays, scientists and meteorologists monitor for weather scientists since all
speed of wind, cloud formation, temperature the weather activities like raining,
changes, rainfall and snowfall, etc. using satellite thundering etc. occurs here.
images. Weather forecasting through satellite data are more accurate. They give live
data and immediately warn the world if any catastrophic weather events are predicted.
FACT WITH REASON
Weather forecasting is important for mankind.
Weather forecasting is important for mankind because it helps to plan our daily activities,
agriculture, etc.
262 Weather and Climate
Some general ways of forecasting weather
a) Sudden dark or grey clouds can cause heavy rainfall.
b) Rainfall is likely during the daytime or evening if it is hot and sunny and air
is humid from the morning.
c) White clouds high up in the sky and light blue sky suggests a sunny day.
d) Sky covered partially with clouds in the morning may not cause rainfall
during the day.
Department of Hydrology and Meteorology is the main body in Nepal which is
responsible for weather forecasting. There are meteorological stations in every
districts of Nepal. Meteorologists interpret the data obtained from the station and
provide us the related information about the weather. Position of clouds, wind speed,
temperature, humidity, air pressure, etc. are observed carefully to predict weather.
On the basis of the predicted weather, we can plan our activities like visits, holiday
plans, trips, games, etc.
Importance of weather forecasting
1. Early prediction of harsh weather can save several lives and property.
2. It helps to take precautions in planning the routes for air transportation and
ocean navigation.
3. It helps in agricultural sector by providing information about appropriate
time for tilling, sowing seeds, harvesting crops, etc.
4. It helps in the planning the outdoor activities.
STEPS EXERCISE
STEP 1
1. Fill in the blanks with appropriate words:
a) …………….. rainfall occurs when clouds are cooled rapidly into water
droplets as they strike hills and mountains or is raised by them.
b) If the dew point is below the …………….. temperature of water, frost
forms.
c) Ozone absorbs different …………….. rays from the sun.
d) Convection of …………. and …………… air masses results in wind.
e) The standard atmospheric pressure shown by mercury barometer at sea-
level at 00C is …………….. of Hg.
2. Write True for the correct and False for the incorrect statements:
a) Sunlight is one of the important components of weather.
b) Dew usually forms during hot nights.
Modern Concept Science and Environment - 7 263
c) Ionosphere overlaps between the thermosphere and exosphere.
d) Convection of air masses results in wind.
e) Anemometer is used to measure the velocity of the wind.
STEP 2
3. Answer the following questions in one word.
a) Which thermometer is used to measure highest and lowest temperature
of a day?
b) Which layer of atmosphere mostly contains ozone gas?
c) Which device measures atmospheric pressure?
d) Which layer of atmosphere contains maximum mass of air?
e) Which device measures humidity?
4. Write any two differences between:
a) Clouds and rain b) Dew and frost
c) Sea breeze and land breeze d) Troposphere and stratosphere
e) Thermometer and barometer
5. Give reasons:
a) Sunlight is called the most important element of weather.
b) Ozone is known as the protective blanket of the earth.
c) Sea breeze carries moist air while land breeze carries dry air.
d) Hygrometer is a weather instrument.
e) Weather forecasting is important for mankind.
STEP 3
6. Answer the following questions:
a) Define weather. What are weather elements? Give examples.
b) Define climate. What is convection?
c) What is breeze? Why does wind blow?
d) Name two factors that are responsible for movement of wind.
e) Explain how sea breeze occurs.
f) Describe how land breeze occurs.
g) What is atmosphere? Name the layers of atmosphere.
h) Mention any three important features each of troposphere and stratosphere.
i) What do you mean by weather forecasting? List any two important
advantages of weather forecasting.
7. Draw a well labelled diagram showing different layers of atmosphere.
264 The E arEtshtimaantedd tSepaachcineg periods Theory Practical
UNIT 6 2
21 The Earth and Space
Syllabus issued by CDC Solar system
Solar system
Sun and planets
Star and its features
Distance, brilliance and colour of stars
Structure and motion of stars
Differences between stars and planets
Constellations–introduction and description of some famous constellations
Identification of constellations
LEARNING OBJECTIVES
At the end of this unit, students will be able to:
introduce solar system and its members (size, distance, days and year).
introduce planets and stars and differentiate between them on the basis of
surface, colour, temperature and size.
introduce some major constellations.
Key terms and terminologies of the unit
1. Solar system: Solar system is the family of sun including the planets and their
satellites, asteroids, meteors, comets, interplanetary dust and gas.
2. Sun: Sun is the hot ball of gases and the only star present in the solar system.
3. Planets: The heavenly bodies that revolve round the sun in their own elliptical
orbit are called planets.
4. Stars: Stars are gigantic luminous heavenly objects.
5. Light year: Light year is the measure of total distance travelled by the light in a
year.
6. Constellation: A group of few stars in the sky that resembles the shape of religious or
mythological figures, animals or objects is called a constellation.
7. Ursa Major: Ursa Major is the common name of the easily visible constellation in
the northern sky.
Modern Concept Science and Environment - 7 265
8. Ursa Minor: Ursa Minor is the constellation which is a group of seven stars seen
in the shape of dipper.
9. Nuclear fusion: The process by which smaller nuclei of atoms combine to form a
larger nucleus is called nuclear fusion.
10. Galaxy: The group of billions of stars, space, dust and clouds is called galaxy
21.1 Solar System
Solar system is the family of sun
including the planets and their
satellites, asteroids, meteors,
comets, interplanetary dust and
gas. The members of the solar
system are held together by
gravity. The force of gravitation
between the heavenly bodies
helps them to maintain their
position in the solar system.
Similarly, gravitational force of
planets also holds the satellites Solar system
and maintains their revolution round the planet in their own orbit.
Sun
The sun is the most important member of the solar system.
The core of the sun consists of enormous amount of hydrogen
atoms. These hydrogen atoms combine with one another to
form helium atoms. This process is called nuclear fusion.
Nuclear fusion releases enormous amount of heat and light
energy in the sun. The surface temperature of the sun is about
5500°C while its inner core has temperature up to 15.6 million Sun
degree Celsius. It is the nearest star from the earth but looks small because it is 150
million kilometres far from the earth. The sun is a massive star as compared to other
bodies in the solar system. Its radius is 695,508 km which is 109 times larger than the
radius of the earth. It is also 333,000 times more MEMORY PLUS
massive as compared to the earth. The sun is about Almost all life on earth is supported
4.6 billion years old and is expected to shine in the by the sun through photosynthesis.
sky for about another 5 billion years.
266 The Earth and Space
FACT WITH REASON
Sun is star. Why?
Sun is star because sun produces heat and light through nuclear fusion.
Planets
The heavenly bodies that revolve around the sun in their own elliptical orbit are called
planets. There are eight major planets in the solar system. They are: Mercury, Venus,
Earth, Mars, Jupiter, Saturn, Uranus, and Neptune. There are also a number of small,
dwarf planets in the solar system. Some of the dwarf planets are Pluto, Eris and Ceres.
Planets revolve around the sun as well as rotate around their own axis.
A heavenly body that revolves around a planet is MEMORY PLUS
called a satellite. Planets are different from asteroids Planets do not have their own light
and comets. Asteroids and comets are smaller bodies as nuclear fusion does not occur.
that also orbit the stars. Planets do not emit their
own light like stars but reflect the light of the sun. This makes planets shine against
the dim sky.
FACT WITH REASON
Earth is a planet. Why?
Earth is a planet because it is huge round heavenly object revolving around the sun.
First four planets are called inner planets or terrestrial planets. Why?
First four planets are called inner planets or terrestrial planets. Because they are made up of rocks and soil.
Mercury MEMORY PLUS
It is the closest planet to the sun. Mercury is made up of mostly rock
It is also the smallest planet of and heavy metals.
the solar system which is only a bit larger than the moon. The side
of Mercury facing the sun is very hot as the temperature reaches
up to 4500C. But,the side facing away from the sun is very cold.
Temperature drops far below the freezing point. Mercury has no Mercury
Venus
water and atmosphere to sustain life.
Venus
Venus is the second closest planet MEMORY PLUS
from the sun. It is the hottest and Venus does not have any satellite.
brightest planet in the solar system.
Venus is the hottest planet because of the thick gases that trap solar
heat. The pressure of the atmosphere is so high that it can crush living
organisms and kill them. But, it does not support life. Venus spins
Modern Concept Science and Environment - 7 267
slowly from east to west while most of other planets revolve from west to east. It is also
called morning star and evening star because it appears in early morning in the eastern
sky and in evening in western sky. It has also been discovered by the ancient people.
FACT WITH REASON
Venus is called evening star. Why?
Venus is called evening star because it is seen in the western sky of earth in evening.
Earth
Earth is the third planet from the sun. About 71% of the earth is Earth
covered by water and remaining 29% by land. It has atmosphere
primarily of nitrogen, oxygen and inert gases. It appears blue from
the space due to the reflection of blue light by water. Therefore, this
planet is also known as blue planet. It is the only planet known to
sustain life. The important reasons for the survival of living beings
on the earth are mentioned below:
i) The atmosphere of the earth contains nitrogen, MEMORY PLUS
oxygen and carbon dioxide that are vital for Earth is only planet in the solar
system where life exists.
animals and plants.
ii) It contains an ozone layer in the atmosphere that protects us from harmful ultra
violet rays coming from sun.
iii) Its atmosphere contains greenhouse gases like carbon dioxide, methane, water
vapour, etc. that maintains the earth’s temperature constant.
iv) Plenty of salt water and fresh water is available for living organisms.
FACT WITH REASON
Earth is also known as the only living planet. Why?
Earth is also known as the only living planet because it is the only planet where life is present
due to water, appropriate temperature and suitable atmosphere.
Mars
The fourth planet from the sun MEMORY PLUS
is the Mars. It is a cold and dusty The atmosphere of Mars contains
terrestrial planet. The dust of iron thin of carbon dioxide.
oxide i.e. Limonite rock gives the planet its reddish appearance. So,
it is also known as red planet. Mars shares similarities with Earth as Mars
it has mountains, valleys and storm systems. Its polar regions are capped by water
ice and frozen carbon dioxide. Its atmosphere does not have sufficient oxygen for the
survival of living beings. Mars is visible to the naked eyes.
268 The Earth and Space
FACT WITH REASON
Mars is called a red planet.
Mars is called a red planet because of its reddish appearance due to the limonite rocks.
Jupiter
Jupiter is the fifth planet from the sun MEMORY PLUS Jupiter
and is the first outer planet. It is the Jupiter is the fastest rotating planet
largest planet in our solar system. It is in our solar system. Its days are only
a gaseous planet composed mostly of 10 hours long.
hydrogen and helium and other trace gases. Giant Red Spots are seen due to giant storm
on the surface of Jupiter. Jupiter has 67 satellites. It is also visible to the naked eyes.
Saturn
Saturn is the sixth planet from the MEMORY PLUS Saturn
sun and it is the second largest As the 5th brightest object in our
planet of the solar system. It is also solar system, Saturn can be seen
a Jovian planet and is composed of with the naked eye and by using
mostly hydrogen and helium gases. binoculars
This planet is well known for its beauty due to the presence of attractive gaseous rings.
It has 62 satellites. It appears as one of the brightest yellowish object in the night sky.
FACT WITH REASON
Saturn is called a Jovian planet.
Saturn is called a Jovian planet because it is massive like that of Jupiter.
Uranus
Uranus is the seventh planet from MEMORY PLUS
the sun. Uranus also rotates on its Uranus is the first planet to be
own axis from east to west. It has discovered by the use of a telescope.
an atmosphere of hydrogen, helium, methane and other gases. It
has 27 satellites and faint rings. Uranus
Neptune
Neptune
Neptune is the eighth and the MEMORY PLUS
farthest planet from the sun. It is Neptune is not visible with naked
known for the strong winds which eyes.
sometimes blow faster than the speed of sound. This cold planet
has a rocky core. Its atmosphere is composed of hydrogen, helium,
neon, etc.
Modern Concept Science and Environment - 7 269
FACT WITH REASON
Neptune is coldest planet. Why?
Neptune is coldest planet because it is farthest from sun. So no heat reaches up to Neptune.
Table of details of planets of solar system
S. Name of the Average Average Period of rotation Period of Number
(hour, days)
No. planet distance diameter revolution of
from the sun (in km) (days/years) satellites
(in km)
1. Mercury 5.76 × 107 4851.2 58.85 days 87.97 days 0
2. Venus 10.7 × 107 12035.2 243.02 days 224.7 days 0
3. Earth 14.88 ×107 12672 23 hrs. 56 min. 365.25 days 1
4. Mars 22.56 × 107 6742.4 24 hrs. 37 min. 22 sec. 286.98 days 2
5. Jupiter 76.8 × 107 1139040 9 hrs. 55 min. 30 sec 12 years 67
6. Saturn 144 × 107 115811.2 10 hrs. 30 min. 29.5 years 62
7. Neptune 288 × 107 50441.6 17 hrs. 14 min. 24 sec. 84 years 27
8. Uranus 448 × 107 48972.8 16 hrs. 6min 36 sec. 164 years 13
Source: World Almanac – 2007 AD
21.2 Stars
Stars are those heavenly bodies that shine brightly in the sky by producing light on
their own. They look small as they are very far from the earth. They are the massive
ball of hot gases. Modern astronomers believe there are more than 1022 stars in
the universe. Different stars have different sizes. The sun is also a star. Some stars
are bigger than the sun, some as big as it and some are smaller than the sun. The
white dwarf stars are about the size of the Earth. Of all the stars in the universe, the
sun is a medium sized star. It is also the nearest star from the earth. Others stars
are not visible during the day time due to the dominance of the light of the sun.
FACT WITH REASON
Why cannot we see any stars during day?
We cannot see any stars during day because sunlight is too much dominant than light from
other stars.
Structure of stars MEMORY PLUS
The sun is also a star which is only
Stars are extremely hot masses of gases. The gases source of heat and light energy for
are primarily hydrogen and helium. The star all the members of solar system.
is composed of enormous amount of hydrogen
270 The Earth and Space
nuclei. Each light hydrogen nucleus fuses with other hydrogen nucleus and forms
heavier helium nucleus. This reaction is called nuclear fusion. Nuclear fusion releases
tremendous amount of energy in the form of heat and light.
FACT WITH REASON
Star is luminous. Why?
Star is a luminous body because fusion of hydrogen in its core emits light.
Brilliance of stars
Brilliance is the extra brightness of the star. Nuclear fusion reaction in the core of
stars produces huge amount of heat and light and is the cause of brilliance of stars.
Brightness of a star completely depends upon the quantity of hydrogen nuclei in
its core. Size of the star, surface temperature and distance from the earth are other
important factors which determine the brightness of the star.
FACT WITH REASON
Why do some stars look brighter than others in night sky?
Some stars look brighter than other star because they are young with lots of hydrogen or
these are nearer than other ones.
Colour of stars
The colour of the star depends on its brightness. The brightness depends upon its
surface temperature. The star with highest temperature looks blue and the star
with lowest temperature is red. Blue stars are young stars with enormous quantity
of hydrogen atoms for nuclear fusion while red stars are old stars with decreased
hydrogen atoms for nuclear fusion. The table below shows that colour of stars and
their surface temperature.
Colour Blue (Hottest) White Yellow Orange Red (Coolest)
Temperature 25,000oC 11,000oC 6,000oC 4,000oC 3,000oC
Distance of star
Stars are so far from the earth. Their distance cannot be measured by traditional
measurement system like meters, kilometres etc. So a special unit is used in astronomy
to measure such vast distance. The unit is called light year. Light year is the measure
of total distance travelled by light in one year. Do you wonder how much distance is
travelled by light in a year?
1 light year distance
= the speed of light x 1 year time (Since, distance = speed x time)
Modern Concept Science and Environment - 7 271
= 300000 km/s × 365 days MEMORY PLUS
= 300000 km/s × 365 × 24 days 1 parsec is equals to 3.26 light year.
= 300000 km/s × 365 × 24 × 60 × 60 seconds
= 9.5 × 1012 km
1 light year is equivalent to the distance of 9.5 × 1012 km. After the sun, a star named
Proxima Centauri is the nearest star. It is 4.3 light years far from the sun. Can you
calculate its distance in Km?
FACT WITH REASON
Light year is preferred in measuring distance in astronomy. Why?
Light year is preferred in measuring distance in astronomy because it is simple, easy, short
and expresses large distances in small numbers.
Motion of stars
The stars in the sky seem to resemble various shapes. MEMORY PLUS
But, they are continuously moving with extremely
higher speeds in their galactic centre. They are very Some stars in the galaxy are bigger
than the Sun.
far from the earth and therefore the motion of stars remains unnoticed. The movement
made by stars over a time is called proper motion while the movement of star we may
experience due to rotation of earth is called apparent motion.
Difference between the planets and stars
Planets Stars
1. Planets are the masses of rocks, dust, 1. They are extremely hot masses of
ice and gases. hydrogen and helium gases.
2. Planets have low temperature ranging 2. Stars have very high temperature
from -20oC to 420oC. ranging from 3,000oC to 25,000oC.
3. Nuclear fusion does not occur in 3. Nuclear fusion occurs in all existing
planets. stars.
4. Their size ranges from about 2,288 4. They are generally massive and are
km to 57,200 km radius. bigger than most of the planets.
5. The colour of the planets depends 5. The colour of stars depends on the
on the reflection of their surface. rate of nuclear fusion.
6. They do not emit their own light. 6. They emit their own light.
Constellation
We see many stars in the sky during a clear moonless night. Some of these stars look
brighter while some look dim. If we observe the bright stars carefully, we may see
272 The Earth and Space
them in a small group following patterns of different objects. Thus, a group of few
stars in the sky that resembles the shape of religious or mythological figures, animals
or objects is called a constellation. There are 88 constellations in the sky. Most of these
constellations were discovered by ancient people by drawing their own imaginative
figures based on the pattern of the sky. These names and drawings were accepted by
modern astronomy. Aquarius, Gemini, Ursa Major, Ursa Minor, Virgo, Sagittarius,
Orion, etc. are some of the examples of constellations.
Among the 88 constellations, 12 constellations have MEMORY PLUS
been used as zodiac signs since the ancient time. Constellation is a group of small
They are Aries, Taurus, Gemini, Cancer, Leo, Virgo, number of stars which are arranging
Libra, Scorpio, Sagittarius, Aquarius and Pisces. in definite pattern.
FACT WITH REASON
Constellation is useful to us. Why?
Constellation is useful to us because it helps to make calendar, navigate rocket, etc.
Some famous constellations
1. Ursa Major (Big Dipper/ Great Bear)
Ursa Major is the common name of the easily visible
constellation in the northern sky. Romans named this
constellation as Ursa Major which means great bear. This
constellation is a group of seven bright stars in the shape of Ursa major
dipper. In Hindus mythology, the group of these seven stars
is called “Saptarshi” - which means the seven holy ancient sages. Among seven stars,
4 stars look like the vertex of rectangle and the other 3 stars project from 1 lowest right
vertex with an upward bend at its end and resembling the shape of dipper.
2. Ursa Minor (Little Dipper/ Little Bear)
Like Ursa Major, this MEMORY PLUS
constellation is also a group of Stars of Ursa Major are brighter than
seven stars seen in the shape stars of Ursa minor.
of a dipper. However, stars in
this constellation are dimmer than the stars of Big Dipper. It is
visible in the northern sky during the evenings of winter. Among
the seven stars, four stars join as four vertex of quadrilateral
resembling the shape of bowl of the ladle while the remaining Ursa minor
three stars below form its handle.
Modern Concept Science and Environment - 7 273
Differences between Ursa Major and Ursa Minor are:
S.N. Ursa major S.N. Ursa minor
1 This constellation does not 1 This constellation includes the pole
include the pole star or Polaris. star or Polaris.
2 Stars in this constellation are 2 Stars in this constellation are
brighter than the Ursa minor. dimmer than the stars of Big Dipper.
3. Cassiopeia
Cassiopeia is named after mythological MEMORY PLUS
Ethiopian queen. It is the constellation Cassiopeia is the 25th largest
made up of five stars. When these stars constellation in the night sky.
are joined making a line from first to fifth star, it resembles the shape
of “W” of English alphabet. This constellation is visible in northern sky Cassiopeia
during new moon winter nights. It is observed almost at equal distance to Big Dipper
from the pole star. Pole star also known as North Star. It is easily visible reference star
in the constellation of northern hemisphere.
4. Orion
This constellation is located on the MEMORY PLUS
celestial equator. It is visible in Orion is visible during winter season.
northern sky during winter nights. It is more visible especially in the
It is an elongated constellation with month of January in the sky.
seven stars among which three stars in line form its centre. It represents
a pictorial form of a hunter with its club and sword. Therefore named as Orion
‘Orion’, a hunter in Greek mythology.
Identifications of constellations
Humans have used various landmarks in the sky MEMORY PLUS
to map heavenly bodies for thousands of years.
They have used sky maps in navigation, time Constellations are closer to look in
northern hemisphere.
measurement and tracking of celestial events. Therefore, sky maps or constellation
charts are the major reference for identification of constellations. However, we should
first locate some of the easily identifiable constellations. As Nepal lies in the northern
hemisphere, different constellations can be seen in different seasons of northern sky.
Ursa Major can be easily identified as it has bright seven stars. To the left and above
the Ursa Major, we can see Ursa Minor which also has the imaginary shape of ladle.
Identifying the pole star make the identification of constellation easy.
274 The Earth and Space
STEPS EXERCISE
STEP 1
1. Fill in the blanks with appropriate words:
a) …………….. planets are huge as compared to terrestrial planets and are
gaseous in nature.
b) Presence of ………… layer in the atmosphere of earth protects living
beings from harmful ultra violet rays of the sun.
c) Nuclear fusion releases tremendous amount of ……………. in the form of
heat and light.
d) There are …………… zodiac constellations.
e) ………………. maps are used in navigation, time measurement and
tracking of celestial events.
2. Write True for the correct and False for the incorrect statements:
a) Saturn is the largest planet.
b) Nuclear fusion is the main source of energy in a star.
c) Neptune takes the longest time for the completion of one revolution
around the sun.
d) Neutron stars are small stars.
e) There are hundreds of constellations mapped in the sky.
3. Match the following. i) Reflects sunlight
a) Sun ii) Fusion of light hydrogen nuclei
b) Planets iii) Brightest body after moon
c) Aquarius iv) Zodiac constellation
d) Venus v) Medium sized star
e) Nuclear fusion
STEP 2
4. Answer the following questions in one word:
a) What is the surface temperature of sun?
b) Which planet has a giant red spot?
c) How many kilometres make one light year?
d) Which is the largest planet in our solar system?
e) How many constellation are there?
Modern Concept Science and Environment - 7 275
5. Write any two differences between: b) Mars and earth
a) Planets and stars d) Ursa Major and Ursa Minor
c) Inner planets and outer planets
6. Give reasons:
a) Four inner planets are terrestrial planets.
b) Venus is known as a terrestrial planet.
c) Jupiter is called as a Jovian planet.
d) Mars is a reddish planet.
e) Earth is known as the only living planet.
f) Light year is more preferred in measuring distance in astronomy.
g) Blue coloured stars are the hottest stars.
h) We cannot observe all constellations in a single night from a place.
STEP 3
7. Answer the following questions:
a) What is solar system? What is solar system made up of?
b) Define planets. Name the eight planets in the order of increasing distance
from the sun.
c) What are stars? List out the factors that influence the brightness of the
stars.
d) What is the main source of energy in a star? Why do stars differ in colour?
e) Draw a chart for colour and temperature of the stars.
f) What do you mean by zodiac constellations? Name any six zodiac
constellations.
g) Explain Ursa Major in short.
h) Describe in brief about constellations.
i) Define a light year. What is nuclear fusion reaction?
j) Give one word answer to the following:
i. The hottest planet
ii. Nearest planet from the sun
iii. Farthest planet from the sun
8. Draw the figure of: b) Ursa Major
a) Solar system d) Cassiopeia
c) Ursa Minor
2U76NITE n v i ro nEsmtime natetdatenadchiitngs pBearilodasn cTeheory Practical
10 2
22 Environment and its Balance
Syllabus issued by CDC Environment
Natural resources and their types
Importance of natural resources
Natural resource conservation
Protected areas of Nepal
Water resource, their importance and conservation
Watersheds and wetlands
Elements of environment
Role of humans in environmental balance
LEARNING OBJECTIVES
At the end of this unit, students will be able to:
classify natural resources (perpetual, renewable and non-renewable) and explain
them.
explain the need and importance of natural resources.
introduce protected areas of Nepal (National Park, Wildlife Reserve and Conservation
Area).
introduce water resources, watersheds and wetlands and describe the methods of
conservation of these resources.
identify the factors of environmental balance and explain their importance.
introduce producers, consumers and decomposers and explain their relationship
and importance.
Key terms and terminologies of the unit
1. Natural resources: The resources that are directly provided by the nature
itself are called natural resources.
2. Perpetual resources: Those resources that are unlimited and never finish despite
the continuous human use are called perpetual resources.
3. Renewable resources: Those resources that can be renewed or reproduced even
after they are finished are called renewable resources.
4. Non-renewable resources: Those resources that cannot be renewed or reproduced
after they are finished are called non-renewable resources.
Modern Concept Science and Environment - 7 27277
5. Protected Areas: The public areas of natural, historical or cultural values that
are protected from the influence of human activities are called
protected areas.
6. National Park: National parks are the large areas of reserved land that are
provided special protection due to their scenic, recreational,
scientific or historical importance.
7. Wildlife Reserves: The areas of public land that are preserved and managed to
protect the particular flora and fauna in their natural habitat are
called wildlife reserves.
8. Hunting reserve: A reserved area where wildlife are conserved in their natural
habitat and sometimes hunting is also allowed is called a
hunting reserve.
9. Conservation Area: A separate large area where flora and fauna are conserved by
the locals along with the wise use of natural resources is called
a conservation area.
10. Water Resources: The sources of water like river, pond, lake, sea etc. which are
useful to the living organisms in many ways are called water
resources.
11. Watershed: A watershed is the area that drains the water from rain and
melted snow into the water bodies like rivers and lakes.
12. Wetlands: Wetlands are the areas filled with water temporarily or
throughout the year which grows aquatic plants, shrubs or trees.
13. Abiotic Components: The non-living components of the environment like air, water
soil, etc. are known as abiotic components.
14. Biotic Components: The living components of the environment such as grass, forest,
animals etc. are known as biotic components.
15. Autotrophs: The organisms which can make food by themselves are called
autotrophs.
16. Heterotrophs: The organisms which obtain their food from others are called
heterotrophs. Examples: mushroom, deer, man etc.
17. Producers: Producers are the green plants of the environment that can
prepare their own food by themselves.
18. Consumers: Consumers are the animals that depend upon producers either
directly or indirectly for their food.
278 Environment and its Balance
19. Primary consumers: Primary consumers are those animals that directly feed on
producers.
20. Secondary consumers: Animals that feed on primary consumers are called secondary
consumers.
21. Tertiary consumers: Animals that feed on secondary consumers are called tertiary
consumers.
22. Decomposers: Organisms that feed on dead and decayed organic matter are
called decomposers.
22.1 Introduction
Resources are the sources of Wood, food
materials that can be used by & medicine,
humans to meet their demand. pulp
Resources that are directly
Energy recreation, Food, wool,
fuel recreation
home of Jewelry, glass,
wildlife, cans, ceramics Agriculture
rubber,
provided by the nature itself are Energy
drinking water cotton Construction
called natural resources. Natural shelter
resources include both living
beings and non-living things.
Sunlight, clean water, fresh air,
fertile land, minerals, etc. are the
non-living natural resources.
Similarly, plants and animals are the examples of living natural resources.
Natural resources like air, water, sunlight and land are the most essential resources
for the survival of human as well as other living organisms on the earth. Other natural
resources like forests, wildlife, minerals, etc. are used to meet the survival needs and
to satisfy the demand of life. Human beings use the natural resources directly or
indirectly. For example, using firewood is the direct use of natural resource while
using a table made up of wood is an indirect use. All the substances that are used by
humans are the results of the resources obtained from the nature.
Types of Natural Resources
On the basis of their capacity and availability in the nature, natural resources are
classified into three different types. They are perpetual resources, renewable resources
and non-renewable resources.
i. Perpetual resources
Those resources that are unlimited and never finish despite the continuous
human use are called perpetual resources. Sunlight, tidal waves of ocean,
wind etc. are the examples of perpetual resources. They do not get depleted
Modern Concept Science and Environment - 7 272979
due to human use and always occur in nature. Human do not have control
over such resources.
Ocean Sunlight Tides
FACT WITH REASON
Sunlight is a perpetual natural resource, why?
Sunlight is a perpetual natural resource because it can be obtained on the earth forever till the
earth exists.
ii. Renewable resources
Those resources that can be renewed or reproduced even after they are
finished are called renewable resources. Plants, animals, air, water, fertile
land etc. are the examples of renewable resources. However, overuse of
renewable resources can make it scarce for a long time. For example, grass is
a renewable resource. But, when animals overgraze on it faster than its rate
of growth, then it may be scarce in that place. Similarly, when fertile land is
used in an improper manner and trees are cut around it, it will turn into a
dry land. The productivity of crops then decreases heavily.
FACT WITH REASON
Why is grass an example of renewable resource?
Grass is an example of renewable resource because it can regrow time and again even after
cutting or grazing.
iii. Non-renewable resources
Those resources that cannot be renewed or
reproduced after they are finished are called
non-renewable resources. Metallic and non-
metallic minerals, diesel, petrol, natural gas,
coal, etc. are the examples of non-renewable
resources. Once these natural resources are
depleted, they cannot be used again within
the human time scale as they take more than Coal
thousands or millions of years to get deposited back in the nature.
280 Environment and its Balance
Petroleum products are used for many purposes like running vehicles and
industries, burning, etc. They largely fulfil the energy demand of the world.
If they are overused, they finish faster and if they are used wisely, they take
time to finish. But, they get finished one day that is for sure. When they
finish, they create energy crisis. Therefore, non-renewable resources should
be used very carefully.
FACT WITH REASON
Minerals and fuels should be used wisely, why?
Minerals and fuels should be used wisely because these are non-renewable resources.
Differences between renewable resources and non-renewable resources.
S.N. Renewable resources S.N. Non-renewable resources
1 Those resources that can be 1 Those resources that cannot be
renewed or reproduced even after renewed or reproduced after
they are finished are called non- they are finished are called non-
renewable resources. renewable resources.
2 Renewable resources can be 2 Non-renewable resources cannot
regenerated. Example: forest, be regenerated. Example: coal,
water etc. petrol etc.
ACTIVITY 1
What types of natural resources are used at home in terms of cooking, lightening and
household heating? List them to fill the table below. One of them is done for you.
Purpose Name of energy source Types of resources
1. Room Heating
2. Cooking
3. Lightening
4. Running electrical appliances Hydroelectricity (water) Renewable
Importance of Natural Resources
Natural resources are the backbone of mankind and development. Human alone
cannot exist in this environment in the absence of natural resources. Humans need
both living and non-living natural resources for the survival of their future generations.
The importance of natural resources is mentioned below:
Modern Concept Science and Environment - 7 282181
a) Food : Green plants use carbon dioxide and water in presence of sunlight to
prepare food. This food energy transfers from plants to animals when animals
eat plants. Both plants and animals are the sources of food for humans.
b) Fresh air : Photosynthesis in plants not only provides food, but also oxygen.
Oxygen is needed for all living beings for respiration.
c) Water : Water is another important resource. All the living beings including
human obtain water from the nature.
d) Habitat : Land is the other important resource of nature on which all living
beings depend. Plants grow on land. Plants and animals including human
live on land. Development activities are carried out on land. Forest, which is
a very important resource also grows on land.
e) Fuels and minerals : The sources of fuel like wood, uranium, coal, petrol,
natural gas etc. come from nature. Minerals like gold, limestone, iron, copper
etc. that are needed for infrastructure development also come from nature.
f) Day to day products : All the day to day products we use like wood, clothes,
medicine, soap, toothpaste, perfume, pen, copy and almost everything are
manufactured by industries using water, forest products, minerals etc. The
source of these substances is the nature.
g) Income : Protected natural resources like national
parks and wildlife reserves, beautiful places like
rivers, mountains, valleys, gorges, etc. attract locals
and foreigners. This also helps in the economic
growth of the country through the collection of
revenue.
Conservation of Natural Resources Tourism
As we know that everything comes from the nature directly or indirectly. Survival and
existence without natural resources is impossible. Human beings are depleting the
natural resources very haphazardly. This can result in the scarcity of these resources
in the near future. Therefore, it is very necessary to conserve natural resources. The
best way of conserving natural resources is by limiting their overuse and using them
in a sustainable manner. Allocating protected areas, harvesting forests scientifically,
afforestation and reforestation, controlling pollution etc. can conserve natural
resources in long term.
22.2 Protected Areas of Nepal
The public areas of natural, historical or cultural values that are protected from the
influence of human activities are called protected areas. The government of Nepal has
established several national parks, wild life reserves, conservation areas and hunting
reserves by realizing the need of protection of natural resources.
282 Environment and its Balance
Api Nampa CA Shey-phoksundo NP
Rara NP Annapurna CA
Khaptad NP
Suklaphanta NP Manaslu CA
Bardia NP
Blackbuck CA Banke NP Dhorpatan HR Langtang NP
Chitwan NP
Shivapuri Sagarmatha NP
Nagarjun NP Makalu-Barun NP
National Park (NP)
Buffer Zone Gaurishankar CA Kanchanjunga CA
Conservation Area (CA) Parsa NP
Wildlife Reserve (WR)
Koshi Tappu WR
Hunting Reserve (HR)
Protected areas of Nepal
The details of those protected areas are discussed briefly in this unit.
FACT WITH REASON
Why does the government declare protected areas?
The government declares protected areas to protect natural resources, wildlife, herbs, forests,
wetlands etc. so that the future generation can see and utilize them.
National Park
National parks are the large areas of public land that are provided special protection
due to their scenic, recreational, scientific, or historical importance. In Nepal, there are
twelve national parks out of which two national parks (Chitwan N.P and Sagarmatha
N.P) are enlisted by the UNESCO (United Nations Educational, Scientific and Cultural
Organization) as world heritage site.
People can visit national parks for recreation, scientific researches, etc. by taking
permission from concerned authorities. But, they should not disturb or destroy the
plants, wildlife, landscape etc. present in those areas. The national parks of Nepal are
discussed below.
Modern Concept Science and Environment - 7 282383
S.N. National Park S.N. National Park
1. Chitwan National Park 7. Khaptad National Park
2. Sagarmatha National Park 8. Makalu Barun National Park
3. Lantang National Park 9. Shivapuri-Nagarjun National Park
4. Rara National Park 10. Banke National Park
5. Bardia National Park 11. Shuklaphanta National Park
6. Shey Phoksundo National Park 12. Parsa National Park
1. Chitwan National Park
Chitwan national park is the oldest national MEMORY PLUS
Chitwan National Park is the oldest
park of our country. It was established in national park of Nepal.
2030 B.S. (1973 A.D.). It is located in the inner Chitwan National Park was enlisted
Terai region of central Nepal. It extends over by the UNESCO as a world heritage
Chitwan, Parsa and Makwanpur district site in 2041 B.S. (1984 A.D.).
covering an area of 932 square kilometres (km2).
Chitwan National Park is famous for One-horned rhinoceros, Royal Bengal tiger
and Gharial. Other important animals of the park are sloth bear, gaur, wild
elephant, pangolin, antelope, Asiatic python etc. The major birds of Chitwan
National park are Bengal florican, lesser florican, giant hornbill, black stork,
white stork etc. Trees like Sal, Sisso, Khair, Simal and grasses like elephant
grasses are major vegetation found in this park.
2. Sagarmatha National Park MEMORY PLUS
Sagarmatha National Park is the second Sagarmatha National Park was the
national park of the country which was first national park of the country
established in 2032 B.S. (1976 A.D.). It is enlisted by UNESCO as a world
located in the northern part of eastern Nepal heritage site in 2039 B.S. (1979 A.D.).
and extends over Solukhumbu district covering an area of 1,148 km2.
Mountain peaks like Lhotse, Nuptse, Ama Dablam, Cho Oyu etc. including the
highest peak of the world, Sagarmatha (Mt. Everest) also lies in this national
park. This park is well known for wildlife like snow leopard, musk deer, red
panda, Himalayan thar, Himalayan mouse hare (Pika), black bear etc. It is also
the habitat of birds like Impeyan pheasant, blood pheasant, snowcock, red billed
chough, etc. Rhododendron, Gobre salla, Thigre salla, Birch, Juniper etc., are the
major vegetation of this park.
284 Environment and its Balance
3. Lantang National Park
MEMORY PLUS
Lantang National Park was established in 2032 Lantang National Park is the country’s
B.S. (1976 A.D.). It is located in the northern first himalayan national park.
part of central Nepal and extends over Rasuwa, The holy lake and Ramsar listed
Nuwakot and Sindhupalchowk districts wetland “Gosainkunda” is located in
covering an area of 1,710 km2. Lantang National Park.
Langtang, Yala Peak etc. are some of the famous mountains in this park. The
national park is well known for its population of red panda, snow leopard,
Himalayan black bear, wild boar, ghoral, serow etc. like wild animals. Different
species of birds including Impeyan pheasant are found in this national park.
Rhododendron, Chir pine, silver fir, Hemlock, Oak, etc. are the major vegetation
of this park.
4. Rara National Park MEMORY PLUS
Rara National Park was established in 2032 Rara National Park is the smallest
B.S. (1976 A.D.). It is located in the northern national park of the country.
part of mid-western Nepal and extends over
Mugu and Jumla district covering an area of The main feature of Rara National
Park is the Rara Lake at an altitude
106 km2. of 2990 m.
Rara Lake, which is the biggest lake of Nepal, is located in this park. The lake is
the habitat for endemic fishes like snow trout. The park is a home for wildlife
like musk deer, Himalayan black bear, leopard, Himalayan tahr, yellow throated
marten, red panda and other animals. Birds like coot, snow cock, grebe, mallard,
common teal, red-crested pochard, gulls and other pheasants including large
numbers of migratory birds are found in this park. Birds from Siberia and
Mansarobar migrate in this national park before the winter arrives. Vegetation
like pine, fir, oak, rhododendron, hemlock, etc. are found in this park.
5. Bardia National Park
Bardia National Park was established in 2045 B.S. (1988 A.D.). It is located in the
southern part of mid-western Nepal and extends over Bardia district covering
an area of 968 Km2.
This park is inhabited by wildlife like royal Bengal tiger, one-horned rhinoceros,
wild elephant, swamp deer, black buck, etc. Rivers in this park are the habitat
for gharial, marsh mugger crocodile, Gangetic dolphin etc. Bird species found
in this park includes Bengal florican, lesser florican and Sarus crane and other
several species of migratory birds. The Sal trees dominate the forest in this
national park. It also has a number of grasslands with several species of snakes
and lizards.
Modern Concept Science and Environment - 7 282585
6. Shey-Phoksundo National Park
Shey-Phoksundo National Park was MEMORY PLUS
established in 2040 B.S. (1984 A.D.). It is located Shey Phoksundo National Park is the
largest national park of Nepal.
in the northern part of mid-western Nepal Shey Monastery and Phoksundo
and extends over Mugu and Dolpa districts Lake are the famous religious and
covering an area of 3,555 Km2. It is the largest natural heritage of Shey-Phoksundo
national park.
national park of the country.
Shey-Phoksundo National Park is the home for a large number of wildlife
including snow leopard, grey wolf, musk deer, blue sheep, ghoral, great Tibetan
sheep, Himalayan tahr, leopard, jackal, Himalayan black bear and yellow-
throated marten. The major birds found in this park are Tibetan partridge,
wood snipe, white-throated tit, wood accentor, and crimson-eared rose finch,
Impeyan pheasant, Chir pheasant, etc. Major vegetation found in this park are
blue pine, spruce, hemlock, cedar, silver fir, poplar, rhododendron, Juniper and
white Himalayan birch.
7. Khaptad National Park
Khaptad National Park was established in 2040 B.S. (1984 A.D.). It is located in
hilly region of far-western Nepal and extends over Accham, Bhajang, Bajura and
Doti districts covering an area of 225 km2.
This national park got its named from “Khaptad Baba”, a famous religious sage
of that region. Ramaroshan Lake is the famous lake in this park. The park is
inhabited by wildlife like barking deer, wild boar, ghoral, Himalayan black bear,
Yellow-throated Marten, Rhesus and Langur monkey, leopard, wild dogs, jackal,
musk deer etc. Common birds in this park are Impeyan pheasant, flycatchers,
partridge, bulbuls, cuckoos, eagles etc. The park consists of trees like sal, pine,
fir, spruce, hemlock, oak, birch and rhododendron. Grasslands in this park are
beautified by wild flowers like primulas, buttercups, wild berries.
8. Makalu Barun National Park
Makalu Barun National Park was established in 2049 B.S. (1992 A.D.). It is
located in the northern part of eastern Nepal and extends over Sankhuwasabha
and Solukhumbu districts covering an area of 2,330 km2.
This national park got its name from Mount Makalu and Barun valley. It is
home for a number of wildlife including snow leopard, clouded leopard, wild
boar, Tibetan hare, red panda, musk deer, barking deer, etc. Different species of
birds including Wren babbler, ground babbler, etc. are recorded in this place.
This national park is famous for its diverse and rare vegetation. Many species of
rhododendron and orchids are found in this park. Bhojpatra, champ, wild rose,
pine and phirphire are the major vegetation of this park.
286 Environment and its Balance
9. Shivapuri- Nagarjun National Park
Shivapuri-Nagarjun National Park was established in 2058 B.S. (2002 A.D.). It
is located in the northern part of central Nepal and extends over the hills of
Kathmandu, Nuwakot, Dhading and Sindhupalchowk district covering an area
of 159 km2.
Major wildlife in this park are leopard, jungle cat, Himalayan black bear, barking
deer, wild boar, golden jackal, Rhesus monkey, pika, squirrel, etc. Various
species of birds like golden throated barbet, eagle, owl, Flycatcher, Cuckoo etc.
are also found. The park has different types of forests in which trees like pine,
oak and rhododendron etc. are present. This park is also well known for its
diversity in mushroom and butterfly.
10. Banke National Park
Banke National Park was established in 2067 B.S. (2010 A.D.). It is located in the
southern part (Terai and Churia hills) of mid-western Nepal and extends over
Banke district covering an area of 550 km2.
Wildlife like tiger, stripped hyena, four-horned antelope, Asiatic elephant, wild
bear, leopard etc. are found in this park. Birds like giant hornbill, black stork,
Sarus crane, Bengal florican, and lesser florican are common birds of this park. As
it consists of flood plains with grasslands and forest, reptiles like gharial crocodile
and python along with numbers of fish species are found here. Sal, Khayer, Sissoo,
Karma etc. are the major tree species found in the forest of this park.
11. Shuklaphanta National Park
Shuklaphanta National Park was established as a wildlife reserve in 2032 B.S.
(1973 A.D.). In 2017, the status of this protected area was changed to a national
park. It is located in the southern plain of Far-western development region of
Nepal and extends over the Kanchanpur district covering an area of 305 km2.
The Shuklaphanta national park is famous for its large tropical grasslands in
which grass species like imperata (cogon grass), heteropogon, Khagra reed and
saccharum are found. Forest in this national park are dominated by tree species
like Sal, Khayer and Sissoo. This national park is well known for its population
of swamp deer in which more than thousand swamp deer can be seen in a herd.
Other wild animals in this park are Royal Bengal tiger, sloth bear, elephant,
hispid hare, leopard etc. Amphibians like mugger crocodile,Asiatic rock python,
cobra and krait are also found in this national park. Common birds found in
this national park are Bengal florican, swamp francolin, spot-bellied eagle-owl,
oriental pied hornbill, babbler, sarus crane etc.
Modern Concept Science and Environment - 7 282787
12 Parsa National Park
Parsa National park was established as a wildlife reserve in 2040 B.S. (1984
A.D.). In 2017, the status of this protected area was changed to a national park.
It is located in the southern part of eastern development region of Nepal and
extends over an area of 499 km2 covering parts of Parsa, Chitwan, Bara and
Makwanpur districts.
Parsa National Park is well known for the conservation of wild Asiatic elephants.
Other animals found in this park are tiger, sloth bear, wild boar, hog deer, barking
deer, sambar, chital, jungle cat, etc. Reptiles like common Cobra, common and
banded Krait, Python and King cobra are also found in this national park. White
breasted kingfisher, Paradise flycatcher, Golden backed woodpecker, etc., are
the major birds found in this national park. Sal, Khayar and sabai grass are the
common vegetation of this national park.
Wildlife Reserves
The areas of public land that are preserved and managed to protect the particular
flora and fauna in their natural habitat are called wildlife reserves. Wildlife reserves
protect endangered or rare animals in their natural habit. These reserves are restricted
from unauthorized access, trespassing and human activities. Though the government
of Nepal had declared three wildlife reserves, now there is only one protacted area in
the list of wildlife reserves. That is, Koshi Tappu Wildlife Reserve.
Koshi-tappu Wildlife Reserve
Koshi-tappu Wildlife Reserve was established in MEMORY PLUS
2032 B.S. (1973 A.D.). It is located in the southern Koshi-tappu Wildlife Reserve is a
part of eastern development region of Nepal and wetland reserve enlisted as a Ramsar
extends over an area of 176 km2 in Sunsari, Saptari site in 2044 B.S. (1987 A.D.).
and Udayapur district.
This reserve is well known for the conservation of water buffaloes. Other important
animals conserved in this reserve are spotted deer, Asiatic elephant, hog deer, wild
boar, blue bull, rock python, gharial crocodile, Gangetic dolphin etc. It is also famous
for the habitat of large number of birds including the migratory birds even from the
Siberia of Russia. Some of the major birds found in this reserve are Ibis species, shore
birds, swamp partridge, Bengal florican, water cock, fish eagle, swamp florican, etc. The
reserve is rich in grassland and marshy vegetation with forests of Khayer and Sisso.
Hunting reserve
A reserved area where wildlife is conserved in their natural habitat and sometimes
hunting is also allowed is called a hunting reserve. However, the hunter should
take permission from concerned authority and is liable to hunt only the particular
288 Environment and its Balance
species that are approved by the authority. Usually, animals or birds with large and
uncontrolled population are approved for hunting. It is a source of foreign currency
in the country.
Dhorpatan Hunting Reserve is the only hunting reserve in our country. It was
established in 2044 B.S. (1987 A.D.). It is located in the hilly region of western
development region and extends over the parts of Myagdi, Baglung and Rukum
district covering an area of 1,325 km2. Blue sheep is the popular animal in this reserve.
Leopard, Himalayan tahr, wild boar, barking deer, jharal etc. are present in this
reserve. Similarly, some of the major birds in this reserve are chir pheasant, impeyan
pheasant and partridge.
Conservation Area
A separate large area where flora and fauna are conserved by the area authorities and
locals along with the wise use of natural resources is called a conservation area. It has
no special protection status but hunting and poaching of flora and fauna is restricted.
The main objective of establishing a conservation area is to upgrade and develop the
economic status of the local people by the proper use of natural, cultural and historical
resources. There are six conservation areas in our country. They are:
1. Annapurna Conservation Area
2. Manaslu Conservation Area
3. Kanchanjunga Conservation Area MEMORY PLUS
4. Api-Nampa Conservation Area
Annapurna Conservation Area
Project is one of the successful
5. Gauri Shankar Conservation Area conservation projects managed
6. Krishnasar Conservation Area by National Trust for Nature
Conservation (NTNC).
1. Annapurna Conservation Area Krishnasar Conservation Area was
Annapurna Conservation Area is the largest designated for the conservation of
Krishnasar or black buck.
and oldest conservation area of the country.
It was established in 2049 B.S. (1992 A.D.). It is located in the northern part of
the western development region and extends over the parts of Kaski, Lamjung,
Myagdi, Mustang and Manang district covering an area of 7,629 km2.
This conservation area is named after Mount Annapurna. It is rich in biological
and cultural diversity. It includes 22 different forest types with 1226 species of
plants, 101 species of mammals, 474 species of birds, 39 species of reptiles and
22 species of amphibians. Annapurna conservation area is managed by National
Trust for Nature Conservation (NTNC). Annapurna Circuit is the most famous
trekking route in this conservation. NTNC collects revenue from tourists visiting
this area and utilizes that in the development of the local area and people.
Modern Concept Science and Environment - 7 282989
2. Kanchenjunga Conservation Area
Kanchanjunga Conservation Area was established in 2054 B.S. (1997 A.D.). It is
located in the northern part of eastern development region and extends over an
area of 2,035 km2 in Taplejung district. Tibet lies in its northern boundary and
Sikkim in the eastern boundary.
This conservation area is named after mount Kanchenjunga that lies in this area.
It is the habitat for various species of wildlife and plants. It is famous for its rich
diversity of rhododendron. Out of 30 species of rhododendron found in Nepal,
24 species are here in this area. Other vegetation include pine, oak, larch, maple,
fir, birch etc. Wildlife in this area includes animals like snow leopard, Himalayan
black bear, Ghoral, Wild boar, musk deer, Nayan, red panda, blue sheep etc.
Birds like snow cock, golden breasted fulvetta (swarnabaksha fulbutta), blood
pheasant, red-billed chough etc. World Wildlife Fund (WWF) and International
Centre for Integrated Mountain Development (ICIMOD) are involved in the
development of people within this conservation area.
3. Manaslu Conservation Area
Manaslu Conservation Area was established in 2055 B.S. (1998 A.D.). It is located
in the northern part of western development region in Gorkha district of Nepal
and covers an area of 1,663 km2. Its boundary extends up to Tibet in the north
and Annapurna Conservation Area in the west.
This conservation area got its name from Mount Manaslu that lies in this area.
It is a habitat of 2000 species of plants and 11 types of forest. Among wildlife, 33
species of mammals, 110 species of birds, 11 species of butterfly and 3 species of
reptiles are found in this area. Major wildlife includes clouded leopard, musk
deer, Himalayan tahr, blue sheep, etc. It also contains unique cultural resources.
4. Api Nampa Conservation Area
Api Nampa Conservation Area was established in 2066 B.S. (2010 A.D.). It is
located in the northern part of far western development region and extends over
an area of 1,903 km2 in Darchula district. It is bounded by Mahakali River in the
west and Tibet in the north.
This conservation area is named after Mount Api and Nampa which lie in this
area. Vegetation like pine, oak, fir, hemlock, juniper, rhododendron etc. are
found in this conservation area. High value endangered medicinal plants like
Yashagumba, Jatamashi, Panchaunle, Kutki, Talispatra, Sugandhawal etc. are
found here. It is the habitat of animals like snow leopard, clouded leopard, musk
deer, Ghoral, Himalayan black bear, serow, Himalayan tahr, etc. and birds like
Impeyan pheasant, Snow Cock, Blood pheasant, Red billed chough and Yellow-
290 Environment and its Balance
billed chough.
5. Gaurishankar Conservation Area
Gaurishankar Conservation Area was established in 2066 B.S. (2010 A.D.). It is
located in the northern part of central development region of the country and
extends over an area of 1,179 km2 in Ramechhap, Dolakha and Sindhupalchowk
districts of Nepal.
This conservation area is named after mount Gaurishankar of Dolakha district. It
is also rich in biological and cultural diversity. Pine, oak, maple and rhododendron
are the common vegetation found in this conservation area. It is the habitat of
wildlife like clouded leopard, red panda, wild boar, musk deer, python etc.
Impeyan pheasant, babbler etc. are the important birds found in this area.
6. Krishnasar Conservation Area
Krishnasar Conservation Area was established in 2065 B.S. (2010 A.D.). It covers
an area of 16.95 km2 and is located in the Bardia district. It is the conservation area
of Nepal that was designated to conserve the endangered Krishnasar (black buck).
ACTIVITY 2
Visit any of the protected area of Nepal and list the following details.
Name of Protected Area:
Major animals/ Major birds/ Major plants/ Natural features Cultural/
Religious/
S.N. Endangered Endangered Endangered (Mountains, Historical
features
animals birds plants Lakes)
1.
2.
3.
22.3 Water Resources
The sources of water like river, pond, lake, sea etc. which are useful to the living
organisms in various ways are called water resources. About 70% of the earth’s surface
is covered by ocean, however they have limited use for humans. About 97% of all
water of the earth’s surface is ocean water. The fresh water of rivers, ponds, lakes etc.
is only about 3%. Fresh water of the earth is stored in glaciers, mountain caps, rivers
and ground water.
Modern Concept Science and Environment - 7 292191
Sources of Water
Surface water, ground water and rain water are three different sources of water. Water
that is available on the surface of the earth like springs, streams, rivers, ponds, lakes
etc. is called surface water. Water under the surface of the earth is called ground water.
Water that comes from rain is called rain water. Nepal is rich in water resources as it
has large number of rivers and lakes that are formed by icy mountains.
FACT WITH REASON
Nepal is rich in water resources, why?
Nepal is rich in water resources because of the snow stored in Himalayan range and vast
amount of forest which gives rise to many rivers, lakes etc.
Importance of water resources
Water is essential to all living organisms to sustain their life. Humans have also used
water as one of the important resources in various sectors like domestic purpose,
industries, agriculture, transport, recreation, generating electricity etc. The major
importance of water resources are:
1. For domestic purposes like cooking, bathing and to maintain sanitation.
2. For industrial use like mining, food processing, medicine making, metal
processing, etc.
3. For generating hydro-electricity
4. For irrigating lands which is necessary to increase yield of crops
5. For rearing fishes and other aquatic products
6. To provide waterways for ships to transport people and goods in a cheap price.
7. For different recreational activities like swimming, fishing, boating, rafting,
photography, etc.
Conservation of Water Resources
Over consumption of water resources and pollution have caused the degradation
of water resources. Also, the sources of water on the earth are limited. But, the use
of water resources is unlimited. This unlimited use may result in water crisis in the
coming future. Therefore, it is essential to conserve water resources not only for us
but for all the living system and environment. Control of water pollution is one of the
major steps to conserve water pollution. Decreasing deforestation, saving trees and
reforestation also conserve water sources in long term. The use of water should be
wise in urban areas where there is a shortage of water.
292 Environment and its Balance
ACTIVITY 3
List the water resources available in your locality. Categorize them as surface water,
ground water and rain water sources and list the purpose of using such water.
Watershed
A watershed is the area that drains the Rain Precipitation
water from the rain and melted snow into Snow
the water bodies like rivers and lakes. The
size of a watershed may vary from place Watershed divide Tributaries
to place. Based on their size, watersheds Percolation
are also known as catchment area or
drainage basin.
A watershed drains large amount of Percolation
water from its surface to a single water Groundwater
body through large number of branches
called tributaries. Tributaries are the Watershed
networks of small sources of water like rivers and streams that mix with the larger
ones. Some of the examples of watersheds are Shivapuri watershed, Indrasarowar,
Bagmati watershed, etc.
Gandaki, Koshi, Karnali and Mahakali are the four river basins of our country. All rivers
and rivulets end to one of these basins. Shivapuri watershed that lies in Shivapuri-
Nagarjun National park of our country provides water to the people of valley. Water
from rivers like Shyalmati, Nagmati, Bishnumati, etc. of this watershed provide water
to Bagmati River. Bagmati river finally drains water to Koshi River. Similarly, the
area around Indrasarowar (also known as Kulekhani) of Makwanpur district, is one
of the watershed of that area which collects water in Kulekhani dam for hydropower
production. Similarly, area around Begnas lake of Pokhara is a watershed of that lake.
Importance of watershed
Watersheds are the sources of natural resources. They are very important for humans
as well as other living beings. Watersheds are the area with rich biological diversity.
They are the habitat of vegetation and animals from which they get water and food.
Water from the watershed is an important source of drinking water supply and other
domestic purposes like cooking, bathing, cleaning etc. Large watershed provides
water for hydropower production. Similarly, water from the watershed is used in
irrigation. We get fuel wood, fodder, woods, etc. from forested watershed. They are
also the source of various plants and animals that are used in pharmaceutical, food
processing, etc. Similarly, watershed also can be used for recreational activities like
fishing, swimming, boating, etc.
The words you are searching are inside this book. To get more targeted content, please make full-text search by clicking here.
Modern Concept Science and Technology 7
Discover the best professional documents and content resources in AnyFlip Document Base.
Search