Samacheer Kalvi 9th Social Science Geography Solutions Chapter 3 Pdf

Samacheer Kalvi 9th Social Science Geography Solutions Chapter 3 Pdf

Tamilnadu Board Samacheer Kalvi 9th Social Science Geography Solutions Chapter 3: Tamilnadu State Board Solution Class 9 Social Science Geography Chapter 3 – Atmosphere.

Samacheer Kalvi 9th Social Science Geography Solutions Chapter 3: Overview

Board

Samacheer Kalvi
Class

9

Subject

Social Science (Geography)
Chapter

3

Chapter Name

Atmosphere

Samacheer Kalvi 9th Social Science Geography Solutions Chapter 3 Atmosphere

I.) Choose The Best Answers

1.) Oxygenis the mostimportant gas for the survival of livingorganisms.

a.) Helium

b.) carbon-di-oxide

c.) oxygen

d.) methane

2.) The lowest layer of the atmosphereisTroposphere.

a.) Troposphere

b.) Stratosphere

c.) Exosphere

d.) Mesosphere

3.) Ionosphere reflects radio waves.

a.) Exosphere

b.) Ionosphere

c.) Mesosphere

d.) Stratosphere

4.) The process of change of state of waterfrom gaseous to liquid state is called Condensation.

a.) Precipitation

b.) evaporation

c.) transpiration

d.) condensation.

5.) The Sun is the chief energy source of the Earth.

a.) Sun

b.) Moon

c.) Stars

d.) Clouds.

6.) All types of clouds are found in theTroposphere.

a.) Troposphere

b.) Ionosphere

c.) Mesosphere

d.) Exosphere

7.) Alto-cumulus clouds are called ‘Sheep clouds’

a.) Alto-cumulus

b.) Alto-Stratus

c.) Nimbo – stratus

d.) Cirro-stratus.

8.) The Monsoons arePrevailing winds.

a.) Prevailing winds

b.) Periodic winds

c.) local winds

d.) none of the above.

9.) Dew in the form of ice crystals is called Frost.

a.) frost

b.) fog

c.) mist

d.) sleet.

10.) Pressure is called the eye of the storm/cyclone.

a.) Pressure

b.) wind

c.) cyclones

d.) snow.

11.) The vertical movement of air iscalledAir Current.

a.) Wind

b.) storm

c.) Air current

d.) drift.

II.) Match the following

Answer

1.) Meteorology                                                          — Study of weather

2.) Climatology                                                           — Study of climate

3.) Anemometer                                                          — Wind speed

4.) Wind Vane                                                                        — Direction of wind

5.) Mare’s Tail                                                                         — Cirrus

6.) Leeward side                                                         — Rain shadow region

7.) Willy willy                                                                         — Australia

III.) Answer the following Briefly

1.) Define atmosphere

Answer: Different types of gases, water vapour and dust particles in different proportions makes atmosphere. Oxygen and Nitrogen are the permanent gases in the atmosphere with 21% and 78% respectively and composite 99% of the total atmosphere.

2.) Mention the factors that affect the climate?

Answer: Many factors responsible to bring change in the climate some of them are as below

i) Distance from the equator

ii) Altitude

iii) Nearness to the sea

iv) Nature of the prevailing winds

v) Mountain barrier

vi) Cloud cover

vii) Ocean currents

viii) Natural vegetation

3.) Write short note on Lapse rate.

Answer: The temperature decreases at the rate of 6.50C per km of height at altitude. This is the normal lapse rate. The places at the higher altitude will be having lower temperature.

4.) What are the processes responsible forheating the atmosphere?

Answer: Processes like conduction is responsible for the heating the atmosphere, apart from it radiation also increase the temperature of the atmosphere.

5.) Mention the Planetary wind system of the earth.

Answer: Planetary winds are the winds which blows in the same direction throughout the whole year constantly, these winds are also known as permanent winds. Trade winds, Westerlies and Polar Easterlies are some of the examples of planetary winds.

6.) Write short note on:

a.) Trade winds.b. Roaring Forties

Answer: Short note

a) Trade winds: The winds blow from the subtropical high-pressure belt to the Equatorial low-pressure belt in the both of the hemispheres are known as Trade winds. These winds blow regularly with force and they have constant direction throughout the year. These winds help traders for sailing in the seas hence they named Trade winds.

b) Roaring Forties: When Westerlies winds blow from tropical high-pressure belt to the sub polar low-pressure belt they blow very fast with the great velocity. Hence when they blow at 40o it known as Roaring Forties.

7.) How are clouds formed?

Answer: Evaporated air goes up and gets cool down and this coolness makes the vapour condensed and it forms droplets and become saturated and gets heavy and finally takes a form of a cloud.

8.) What are the different types of rainfall?

Answer: There are three types of rainfall

i) Convectional rainfall

ii) Frontal or cyclonic rainfall

iii) Orographic rainfall.

9.) Write short notes on:

a.) drizzle b. rainc. sleet d. snowe. heat

Answer:a. drizzle:From low clouds the minute droplets of water falling with diameter of less than 0.5 are known as Drizzle.

b.) rain: Rain is the widespread form of precipitation in the places having temperature above the freezing point, it happens when there is moisture in the air. The diameter of a rain drop is more than 5mm.

c.) sleet:In the form of pellets made up of transparent and translucent ice the precipitation takes place is known as Sleet. The precipitation is combination of rain and snow.

d.) snow: When vapor in the air get condensed below freezing point then it forms Snow.

e.) hails: The ice chunks having less than 2cm diameter falls from the sky during rainstorm or thunderstorm are known as hails. These hailstones form solid precipitation, small pieces of ice fall downwards. It destroys agricultural crops, injure humans and affect property.

IV.) Give reason

1.) Cyclones cause huge loss of life and property.

Answer: Cyclones causes huge loss of life and property because cyclones are very powerful and cyclonic winds destroys cause huge loss of life and property due to its power. Typhoons, hurricanes, baguios, willy willy are some of the examples of cyclones. Cyclone become weak after reaching the land but still having enough power to destroy structures.

2.) Cloudy days are warmer than cloudless days.

Answer: Cloudy days are water than cloudless days because the when the is hot because of the rays of the sun the heat doesn’t have way to go up in the atmosphere. The heat gets locked on the earth hence we feel the heat. Once the clouds go away the heat gets released and we feel fresh air again.

3.) Fog is dangerous for traffic.

Answer: Fog is dangerous for traffic because in the fog it is difficult to see on the road. Unclear view can cause to accidents hence fog is dangerous for traffic.

4.) Convectional rainfall is also called 4’0 clock rain.

Answer: Convectional rainfall is also called 4’o clock rain because the hot surface of the earth also heats up the air and heated air rise up and expands, it causes convectional air currents and like this the moist in the air cools down and cause convectional rainfall at the evening.

5.) Polar Easterlies are cold and dry. Why it is so?

Answer: Polar Easterlies are cold and dry because, the polar is high pressure belt and the sub polar is low pressure belt. These winds blow from the polar high-pressure belt to towards the sub polar low-pressure belt hence these winds are cold and dry.

V.) Distinguish between the following

1.) Weather and climate

Answer:

Weather Climate
The study of atmospheric conditions over small areas for short time span is considered weather. The study of the average weather conditions for long period of time in big area is considered climate.
Weather can change every day or hour. Climate is permanent and remains the same.
The data of weather is collected every day. Climate is average of the weather data.
The study of weather is known as Meteorology. The study of climate is known as Climatology.

2.) Land breeze and sea breeze

Answer:

Land Breeze Sea breeze
The wind blows from land to sea during night is known is Land Breeze The wind blows from sea to land in the afternoon is known as Sea Breeze.
Land breeze cools down the land during night. The land gets hot during day as compared to ocean.
The cool air sinks and create high pressure. The hot air ascends and it causes low pressure on the adjoining ocean.

3.) Windward side and Leeward side.

Answer:

Windward Side Leeward Side
Windward side is a side of a mountain which faces the prevailing wind. Leeward side is side of the mountain sheltered from the wind.
The windward side receives heavy rainfall. The leeward side is receives very less rainfall.

4.) Tropical cyclone and Temperate cyclones.

Answer:

Tropical Cyclone Temperate Cyclone
Tropical cyclones are formed where temperature is more than 26 to 27o C. Temperate cyclones are formed at front where hot and cold air masses meet.
Tropical Cyclones are formed only in sea. Temperate Cyclones are formed in sea and on land.
Tropical Cyclones weakens after reaching on land. Temperate Cyclone remains strong after reaching land from sea.
Tropical Cyclones occurs in Indian Oceans. Temperate Cyclone occurs over the North Atlantic Ocean, North West Europe, Mediterranean basin.

VI.) Paragraph Questions

1.) Write a paragraph about the structure of the atmosphere.

Answer: Thick layer near the earth surface and thin layer outer side until it merges with space is known as the atmosphere. The Atmosphere is divided into five layers troposphere, stratosphere, mesosphere, thermosphere and exosphere.

i) Troposphere: It is the lowest layer of the atmosphere. ‘Tropos’ in Greek means turn or change. This layer spans up to 8 kms at the poles and up to 18 km at the equator. Temperature varies along with height. Many weathers phenomenon takes place in this layer hence this layer known as weather making layer. Upper limit of this layer is known as tropopause.

ii) Stratosphere: Stratosphere is next layer of troposphere. Stratosphere extends about 50 km up above earth surface. Concentrated ozone molecules are found in this layer hence this layer is known as ozonosphere. In this layer also temperature varies with height. Jet planes fly in this layer. Upper limit of this layer is known as stratopause.

iii) Mesosphere: The area between 50 km to 80 km is known as Mesosphere. In this layer also temperature decreases and increases with height. Meteors burns in this layer. The upper most limit of this layer is known as Mesopause.

iv) Thermosphere: The layer above mesosphere is known as thermosphere. The range of this layer is above 600 km. This layer has composition of gases in the lower thermosphere hence this layer is known as Homosphere. The composition of gases in lower thermosphere is almost even and upper portion of this layer has uneven composition of gases hence upper portion of this layer is known as heterosphere. Temperature of this layer increase with height. In thermosphere there is another layer contains ions and free electrons known as Ionosphere. Radio waves transmitted from earth are reflected to earth from this layer.

v) Exosphere: This is the uppermost layer of the atmosphere. This layer is contained extremely rarefied gases and gradually merge with the outer space. This zone is known for Aurora Australis and Aurora Borealis.

2.) Explain the different types of Permanent winds.

Answer: The winds which are blowing constantly at the same direction for whole year are known as Permanent Wind and also known as Planetary winds. Some of the permanent winds are Trade winds, Westerlies and Polar Easterlies.

i) Trade winds: These winds blow from subtropical high-pressure belt to the equatorial low-pressure belt in both hemispheres. The winds are blows with regularly with same force and in the constant direction. These wind helps traders who sailing in the seas hence these winds are known as Trade winds.

ii) Westerlies: Westerlies blow from the tropical high-pressure belt to the sub polar low-pressure belt in both of the hemispheres. These permanent winds blow from South West to North East in the northern hemisphere and North West to South East in the southern hemisphere. The velocity become vigorous and fast hence it called Roaring Forties at 40O, Furious Fifties at 50Oand Screaming Sixties at 60O

iii) Polar Easterlies: Polar Easterlies blow from the polar high-pressure belt to the sub polar low-pressure belt. These winds are cold and dry, these winds are weak also blow from North East in Northern hemisphere and South East in south hemisphere.

3.) How are clouds classified? Explain them.

Answer: Clouds are classified basis on the height as follows

i) High Clouds: There are three types of high clouds

a) Cirrus: This type of clouds form of white fibrous silky filaments in the high sky around 8000 meters to 12000 meters are known as Cirrus clouds. These clouds contain ice crystals and they are also dry and they don’t rain.

b) Cirro-cumulus: This type of clouds is white patched and they are like sheet made from ice crystals.

c) Cirro-stratus: This type of clouds are milky, smooth, transparent and white. These clouds are made from tiny ice crystals.

ii) Middle Clouds: There are three types of middle clouds

Alto-stratus: These clouds look like thin sheets of grey or blue coloured clouds and appear like uniform. These clouds consist frozen water droplets.

Alto-cumulus: these clouds are fitted closely together in parallel bands hence they called as Sheep clouds or wool pack clouds.

Nimbo Stratus: These clouds are dark-coloured clouds, close to ground. These clouds are associated with rain, snow or sleet.

iii) Low Clouds: There are four types of low clouds

i) Strato-cumulus: Low clouds are formed gray or whitish layer of non-fibrous found in rounded patches at an height of 2500 to 300 metres. These clouds are associated with fair or clear weather.

ii) Stratus: These clouds are dense and like low-lying fog associated with rain or snow.

iii) Cumulus: These clouds are dome shaped clouds with flat base. These clouds associated with fair weather.

iv) Cumulo-nimbus: These clouds are fluffy thick towering thunderstorm cloud capable to make heavy rain, snow, hailstorm or tornadoes.

4.) How are cyclones formed? How are they classified?

Answer: Cyclone is Greek word means ‘coil of snake’. The centre of cyclone is low pressure and surrounding pressure is high and thus spiral forms. The rotating earth make the cyclone move anti clock wise in northern hemisphere and cyclones are clock wise in the southern hemisphere. There are three types of cyclones

i) Tropical cyclone

ii) Temperate cyclone

iii) Extra tropical cyclone

i) Tropical cyclones: The cyclones in Indian ocean are known as Tropical Cyclone. In western Pacific Ocean, typhoons and in Atlantic Ocean, hurricanes are there. In Phillipines it is baguios and in Australia it is Willy Willy. Taifu in Japan is cyclone which often cause big loss of property and life on the coasts and it becomes weak after reaching on the land.

ii) Temperate cyclones: When hot and cold air masses meet in mid-latitude these cyclones occur. These cyclones don’t get weakened when then reach on the land. These cyclones are commonly found upon the North Atlantic Ocean, North West Europe and Mediterranean basin. The cyclone in Mediterranean basin extends up to Russia and India in winter. It is known as western disturbances in India.

iii) Extra tropical cyclones: This cyclone occurs in latitudes between 30Oand 60Oin both of the hemispheres. Extra tropical cyclone is also known as mid-latitude cyclones. Extra tropical cyclones gather energy from varying temperature in higher latitudes. Mild showers to heavy gales are produced by this cyclone. Extra tropical cyclone also produce thunderstorms, blizzards and tornadoes.

5.) Explain the different forms of precipitation

Answer: When condensed water vapor falls down in different form is known as Precipitation. The cloud water droplets become saturated and fall when the dew point reaches in the cloud and this is the reason of the precipitation on the earth. Precipitation happens in different forms like drizzle, rain, sleet, snow, hail etc.

i) Drizzle: Many uniform minute droplets of water with diameter of less than 0.5 mm falls it known as drizzle. Drizzle happens from low clouds. Many of the time drizzles and fog happens together where it is tough to see.

ii) Rain: Rain happens when abundant moisture in the air. Diameter of a drop of rain is more than 5 mm. Rain is very important form of precipitation in the places having temperature above the freezing point.

iii) Sleet: When pellets of transparent and translucent ice precipitated it called sleet. It is mixture of snow and rain.

iv) Snow: When condensation happens below freezing point snow is formed. Snow is the precipitation of opaque and semi opaque ice crystals. These ice crystals collide and stick together it called snowflakes.

v) Hails: Hails are basically ice chunks having diameter more than 2 cm. Hails precipitated when there is rainstorm or thunderstorm. When small pieces of ice fall it called Hailstones. Hailstones are destructive and affect agricultural crops and human lives.

Updated: July 20, 2021 — 10:07 pm

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