9th Social Science - Book Back Answers - Geography Unit 3

9th - Social Science - Book Back Answers - Geography Unit 3 - English Medium

Tamil Nadu Board 9th Standard Social Science - Geography Unit 3: Book Back Answers and Solutions

This post covers the book back answers and solutions for Unit 3 – Geography from the Tamil Nadu State Board 9th Standard Social Science textbook. These detailed answers have been carefully prepared by our expert teachers at KalviTips.com.

We have explained each answer in a simple, easy-to-understand format, highlighting important points step by step under the relevant subtopics. Students are advised to read and memorize these subtopics thoroughly. Once you understand the main concepts, you’ll be able to connect other related points with real-life examples and confidently present them in your tests and exams.

By going through this material, you’ll gain a strong understanding of Geography Unit 3 along with the corresponding book back questions and answers (PDF format).

Question Types Covered:

1 Mark Questions: Choose the correct answer, Fill in the blanks, Identify the correct statement, Match the following
2 Mark Questions: Answer briefly
3, 4, and 5 Mark Questions: Answer in detail

All answers are presented in a clear and student-friendly manner, focusing on key points to help you score full marks.

All the best, Class 9 students! Prepare well and aim for top scores. Thank you!

Topic: Unit 3. ATMOSPHERE

I. Social | Choose the correct Answer

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II. Social | Fill in the blanks

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III. Social | Find out the correct statement

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IV. Social | Match the following

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V. Social | Distinguish Between

Distinguish between:

1. WEATHER	CLIMATE
* Weather is the study of atmospheric conditions for short duration over small areas. * Weather data is collected every day.	* Climate is he study of the average weather condition observed over a long period of time for a longer area. * Climate is average of the weather around 35 years
2. LAND BREEZE	SEA BREEZE
* The wind that blows from land to sea is called Land breeze. * It brings dry weather.	The wind that blows from ocean to land is called Sea breeze. It brings rainfall.
3. WINDWARD SIDE	LEEWARD SIDE
* The windward is the side of a mountain which faces the prevailing wind. * It receives heavy rainfall.	* The leeward side of the mountain is the side sheltered from the wind. * It receives very less rainfall.
4. TROPICAL CYCLONE	TEMPERATE CYCLONE
* Tropical cyclones develop in the inter tropical convergence zone. * Tropical cyclones causes heavy loss of life and property.	* Temperate cyclones are formed along a front where hot and cold air masses meet in mid latitudes between 350 and 65° N and S both in. * Temperate cyclones do not become weak on reaching the land.

VI. Social | Answer the following briefly

1. Define atmosphere.

The blanket of air that surrounds the Earth is called the atmosphere.

2. Mention the factors that affect the climate.

Disaster from Equator
Altitude
Nearness to the sea
Nature of the prevailing winds
Mountain barrier
Cloud cover
Ocean currents
Natural vegetation.

3. Write a short note on Lapse rate.

The temperature decreases at the rate of 1ºc for every 165 mts of height is known as Lapse rate.

4. What are the processes responsible for heating the atmosphere?

Radiation, Conduction, Convection and Advection.

5. Mention the planetary wind system of the Earth.

The wind which constantly blow in the same direction throughout the year are called the planetary winds.

6. Write short note on a) Trade winds b) Roaring Forties

Trade winds:

Trade winds blow from the subtropical high pressure belt to the Equatorial low pressure belt in both the hemisphere.

Roaring winds:

The velocity of westerlies become so vigorous and fast to be called Roaring Forties at 40°.

7. How are clouds formed?

Cool moisture laden air, gets collected around particles like dust, salt content from the sea, smoke etc., and form clouds.

8. What were the different types of rainfall?

Convectional rainfall
Cyclonic rainfall
Orographic rainfall

9. Write about the notes on:

a) Drizzle b) Rain c) Sleet d) Snow e) Heat

Drizzle:

Falling of numerous uniform minute droplets of water with diameter of less than 0.5 mm is called drizzle.

Rain:

When there is abundant moisture in the air, the diameter of droplets of water is more than 5mm. It is called rain.

Sleet:

Sleet refers to a precipitation in the form of pellets made up of transparent and translucent ice This precipitation is a mixture of snow and rain.

Snow:

It is the precipitation of opaque and semi opaque ice crystals.

Heat:

Heat is a energy which makes objects hot while temperature measures the intensity of heat.

10. How are Cyclones Classified?

They can be classified into

Tropical cyclones
Temperate cyclones
Extra tropical cyclones.

VII. Social | Answer all the questions given under each caption

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

The atmosphere is divided into five layers.

Troposphere
Stratosphere
Mesosphere
Thermosphere
Exosphere

Troposphere:

The layer extends up to 8 kms at the poles and up to 18 kms at the Equator.
The temperature decreases with increasing height.

Stratosphere:

This layer extends up to 50 kms.
Ozone molecules are found in this layer.

Mesosphere:

This layer extends up to 80 kms.
Most of the meteors nearing the Earth get ignited here.

Thermosphere:

It extends up to 600 kms.
Ionosphere is a layer of the thermosphere that contains ions and free electrons.

Exosphere:

This layer merges with the outer space.

2. Explain the different types of permanent winds.

The winds which constantly blow in the same direction throughout the year are called the planetary winds.

These winds include

Trade winds
Westerlies
Polar Easterlies

Trade winds:

They blow with greater regularity in force and in a constant direction throughout the year.
These winds were very helpful to traders who sailing in the seas.

Westerlies:

Westerlies are permanent winds.
The velocity of westerlies become so vigorous and fast.

Polar Easterlies:

Polar Easterlies are cold and dry polar winds.
These are weak winds.

3. How are clouds classified? Explain them.

According to their height clouds are classified into the following types
High clouds are 6-20 kms Height. They are classified into Cirrus, Cirrocumulus and Cirrostratus.
Middle clouds are 2.56 kms Height. They are classified into Alto stratus, Alto cumulus and Nimbostratus.
Low clouds are ground surface to 25 kms height. They are classified into Stratocumulus, Stratus, Cumulus and Cumulonimbus.

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

Cyclones are centres of low pressure where winds from the surrounding high pressure are converge towards the centre in a spiral form.

They can be classified into

Tropical cyclones
Temperate cyclones
Extra tropical cyclones.

Tropical Cyclones:

They are formed due to the differential heating of land and sea.

Temperate Cyclones:

They are formed along in mid-latitudes between both in 25 and 65° N and S.
They do not become weak on reaching the land.

Extra tropical Cyclones:

These are also called as mid-latitude cyclones.
They produce mild showers to heavy gales.

5. Explain the different forms of precipitation.

The main forms of precipitation include drizzle, rain, sleet, snow, hail etc.,

Drizzle:

Falling of numerous uniform minute droplets of water with diameter of less than 0.5 mm is called drizzle.

Rain:

When there is abundant moisture in the air, the diameter of droplets of water is more than 5mm. It is called rain.

Sleet:

Sleet refers to a precipitation in the form of pellets made up of transparent and translucent ice. This precipitation is a mixture of snow and rain.

Snow:

It is the precipitation of opaque and semi opaque ice crystals.

Hail:

Hails are chunks of ice (greater than 2 cm) falling from the sky.