AP Board 9th Class Social Studies Solutions Chapter 4 Atmosphere

AP State Syllabus 9th Class Social Studies Solutions 4th Lesson Atmosphere

9th Class Social Studies 4th Lesson Atmosphere Textbook Questions and Answers

Improve Your Learning

Question 1.
Explain the composition of the atmosphere.

  • The atmosphere is a sea of gases surrounding the Earth.
  • There are many gases in the atmosphere.
  • Of all the gases in the atmosphere oxygen (21%) and nitrogen (78%) dominate.
  • Other gases are in very small percentages, these include argon, neon, carbon dioxide (0.03%), methane, ammonia, ozone, etc.
  • Water vapour accounts for about 0.4% by volume over the whole atmosphere.
  • Apart from these gases the atmosphere also has the fine dust particles called particulates.

AP Board Solutions

Question 2.
Discuss the structure of the atmosphere along with a diagram.
On the basis of the chemical composition the atmosphere is divided into two broad layers. They are -1) Homosphere II) Heterosphere
I) Homosphere : This layer is characterized by uniformity in composition of gases like
Nitrogen, Oxygen, Orgon and Carbondioxide. It consists of the three thermal layers such as Troposphere, Stratosphere and Mesosphere. It extends up to the height of 90 kms.

A) Troposphere :
i) It is the lower most of layers of the atmosphere.
ii) It extends to a height of 8 kms near the poles and about 18 kms at the equator.
iii) It contains 75% of the total gaseous mass of the atmosphere.
iv) The entire weather phenomenon happens in this layer.
v) The life is present in this layer.

B) Stratosphere :
i) This layer extends up to a height of 50 kms.
ii) This layer is free from clouds and associated weather phenomenon.
iii) These conditions are most ideal for flying jet aircrafts.
iv) This layer contains Ozone layer.

C) Mesosphere :
i) It extends up to a height of 80 kms.
ii) Meteorites burn up as they enter this layer from the space.
iii) The temperature starts decreasing with the increase in altitude.

II) Heterosphere : Because of its heterogenous composition this layer is called heterosphere. This layer is above 90 kms of the atmosphere. It has two thermal layers called Thermosphere and Exosphere.
A) Thermosphere:
i) It extends up to 400 kms.
ii) Here the temperature rises rapidly with increase in height.
iii) It contains electrically charged particles known as ions. Hence this layer is called Ionosphere.
iv) Radio waves are reflected back to the earth through this layer.
v) It is also known as ‘Ionosphere’.

B) Exosphere :
i) The upper most layer of the atmosphere.
ii) Very little is known about this layer.
AP Board 9th Class Social Studies Solutions Chapter 4 Atmosphere 1

Question 3.
Differentiate weather and climate.
Write the differences between weather and climate?

  • The difference between weather and climate is a measure of time.
  • Weather is what conditions of the atmosphere are over a short period of time and climate is how the atmosphere “behaves” over relatively long period of time.
  • Weather is basically the way the atmosphere is behaving, mainly with respect to its effects upon life and human activities.
  • Whereas climate is the description of the long-term pattern of weather in a particular area.
  • In most places weather can change from minute to minute, hour to hour, day-to-day and season-to-season. Whereas the climate is the average of weather overtime and space.
  • In short, climate is what we expect whether a hot summer or a cool winter and weather is what you get or experience at present.

AP Board Solutions

Question 4.
Compare and contrast convectional and orographic rainfall.
Comparison between convectional and orographic rainfall:
1) Both types of rainfall are caused by vertical ascent of heated air.
Contrast between convectional and orographic rainfall :

  1. While orographic rainfall is caused when the mountain forces the air to rise over mountain or the elevation in its path; the convectional rainfall occurs when moisture over the heated ground becomes warmer than the surrounding air.
  2. While convectional rainfall is common on summer days in interior part of the continents the orographic rainfall occurs in the windward sides of mountains.
  3. While the orographic rain occurs in the mountainous regions, the convectional rain takes place in the equatorial regions.

Question 5.
Describe the distribution of world rainfall.

  • Between the latitudes 10° and 30° N and S of the equator, due to the trade winds, rainfall is heavier on the eastern coasts, and decreases towards the West.
  • Between the latitudes 40° and 60° N and S of the equator due to the westerlies, the rainfall is heavy on the west coast, and goes decreases towards the East.
  • Low pressure areas, especially around the equator receiver high rainfall than high pressure areas.
  • The rainfall is more over the oceans than on the continent.

Question 6.
How do climatic changes influence the human life?
Due to climatic changes the following changes are taking place.

  1. The climatic changes led to the emergence of large scale environmental hazards such as global warming, increase of green house gases etc.
  2. Development of planet’s flora and fauna is mainly due to climatic changes.
  3. Globally the average sea level has risen by 17 cm in the 20th century.
  4. Climatic changes are affecting food habits and culture of the people of any area.
  5. Due to global warming both the Greenland and Antarctic ice sheets have lost significant amounts of ice.
  6. Thus the climatic changes are influencing human life significantly.

Question 7.
Explain relative humidity.

  • The amount of water vapour present in the atmosphere is called humidity.
  • Relative humidity is the ratio between the maximum water vapour that the air can hold at a given temperature and pressure and the actual amount of water vapour it holds at any given time.
  • For example, at 20°C temperature air can contain 80 gms of water vapour per cubic meter. If the actual water vapour present is 40 gms, the relative humidity is 50%.
  • If the atmosphere has 100% relative humidity, it is known as saturation level.
  • Relative humidity decreases with increase of temperature and decrease of water vapour,
  • In high humidity, our sweat doesn’t cool us because it cannot evaporate.
  • In low humidity we feel more thirsty.

Question 8.
Why does the amount of water vapour decrease rapidly with altitude?
The water vapour is attracted towards the surface or close to the surface due to the gravitational pull of the earth. Hence the amount of water vapour decreases with altitude.

AP Board Solutions

Question 9.
What is Coriolis effect ? And explain its effects.

“Vasco da Gama found the sea route to India using winds to power his ships. Europeans established colonial states in various parts of the world through the wind power”.

What is Coriolis effect and how does it influence the wind system?
1. Because of the impact of Earth’s rotation on its own axis, the winds move slightly to the right in the northern hemisphere, and to the left in the southern hemisphere. This effect is called Coriolis effect.
AP Board 9th Class Social Studies Solutions Chapter 4 Atmosphere 2
3. At the equator the Coriolis effect is ‘O’ and at the poles it is maximum.

The most important effects of Coriolis force are :
a) The deflection of winds and currents in the ocean.
b) It has significant effect on planes and missiles also.
c) In the northern hemisphere these winds move to the right and in the southern hemisphere to the left. This usually creates the westerly winds moving from the subtropical areas to the poles.
d) The Coriolis effect also affects the movement of ocean currents.

Question 10.
Identify the given local winds in the world map.
a) Chinook
b) Loo
c) Simoon
d) Yoma
e) Norwester
f) Mistral
g) Puna
h) Pampero
AP Board 9th Class Social Studies Solutions Chapter 4 Atmosphere 3

Question 11.
Read the para under the title “Effects of Planetary Winds” on page 43 and comment on it.
Effects of Planetary Winds: You would have noted that the pressure and wind systems are actually a result of the impact of Lithosphere and Hydrosphere on Atmosphere. These winds play a crucial role in transporting heat and moisture across the world. That is why no part of the world gets too cold or too hot for life to survive. Had there been no atmosphere (as on the Moon) it would have got intolerably hot in day time or in the tropics and intolerably cold at night or in the Polar regions. However, these winds do not distribute heat or moisture uniformly – which is why we have some parts of the earth quite hot, some parts cooler and some parts with high rainfall and some which are deserts.
Planetary winds are winds that are created in the different Global circulation cells.

  1. Polar Easterlies – blow from pole to 60°
  2. Prevailing Westerlies – blow from 60° to 30°
  3. Trade Winds – blow from 30° to 0°

These winds transport heat and moisture across the world. But the winds do not distribute heat or moisture uniformly.

AP Board Solutions

Question 12.
Collect weather information covered by media such as newspaper, TV, Radio, etc. to understand weather phenomenon.
Weather information of major cities of India on 8, April 2020.

Delhi 47°C Afternoon, Thu 17:04
Jabalpur 50°C Afternoon, Thu 17:04
Chennai 41°C Afternoon, Thu 17:04
Banglore 45°C Afternoon, Thu 17:04
Ahmadabad sere Afternoon, Thu 17:04
Allahabad 39°C Afternoon, Thu 17:04
Pune 34°C Afternoon, Thu 17:04
Poona 25°C Afternoon, Thu 17:04
Haora 33°C Afternoon, Thu 17:04
Surat 32°C Afternoon, Thu 17:04
Madras 41°C Afternoon, Thu 17:04
Calcutta 34°C Afternoon, Thu 17:04
Solapur 40°C Afternoon, Thu 17:04
Muzaffarpur 50°C Afternoon, Thu 17:04
Bulandshahr 37°C Afternoon, Thu 17:04
Ghaziabad 46°C Afternoon, Thu 17:04
Jaipur 37°C Afternoon, Thu 17:04
Kanpur 48°C Afternoon, Thu 17:04
Lucknow 38°C Afternoon, Thu 17:04
M 0 Ranchi 49°C Afternoon, Thu 17:04
Nagpur 53°C Afternoon, Thu 17:04
Visakhapatnam 32°C Afternoon, Thu 17:04
Guwahati 26°C Afternoon, Thu 17:04
Chittoor 46°C Afternoon, Thu 17:04
Indore 37°C Afternoon, Thu 17:04
Coimbatore Peelamedu 35°C Afternoon, Thu 17:04
Kalya n 35°C Afternoon, Thu 17:04
Patna 39°C Afternoon, Thu 17:04
Kozhikode 30°C Afternoon, Thu 17:04
Gwalior 37°C Afternoon, Thu 17:04
Jamnagar 42°C Afternoon, Thu 17:04
Vadodara 38°C Afternoon, Thu 17:04
Mahesana 36°C Afternoon, Thu 17:04
Akola 41°C Afternoon, Thy 17:04
Bhopal 39°C Afternoon, Thu 17:04
Ludhiana 47°C Afternoon, Thu 17:04
Aurangabad 51°C Afternoon, Thu 17:04
Agra 37°C Afternoon, Thu 17:04
Cochin 39°C Afternoon, Thu 17:04
Benares 39°C Afternoon, Thu 17:04

Question 13.
Collect the newspapers from July to December and note down the news related to extreme rainfall in different parts of country.
Average annual rainfall of the states of India

State Meteorological Divisions Average annual rainfall (mm)
Andaman and Nicobar Islands Andaman and Nicobar Islands 2,967
Arunachal Pradesh Arunachal Pradesh 2,782
Assom Assom and Meghalaya 2,818
Meghalaya Assom and Meghalaya 2,818
Nagaland Nagaland, Manipur, Mizoram and Tripura 1,881
Manipur Nagaland, Manipur, Mizoram and Tripura 1,881
Mizoram Nagaland, Manipur, Mizoram and Tripura 1,881
Tripura Nagaland, Manipur, Mizoram and Tripura 1,881
West Bengal Sub-Himalayan West Bengal and Sikkim

Gangetic West Bengal



Sikkim Sub-Himalayan West Bengal and Sikkim 2,739
Odisha Odisha 1,489
Bihar Bihar Plateau 1,326
Bihar Plains 1,186
Uttar Pradesh Uttar Pradesh 1,025
Plain of West Uttar Pradesh 896
Hills of West Uttar Pradesh 1,667
Haryana Haryana, Chandigarh and Delhi 617
Delhi Haryana, Chandigarh and Delhi 617
Chandigarh Haryana, Chandigarh and Delhi 617
Punjab Punjab 649
Himachal Pradesh Himachal Pradesh 1,251
Jammu and Kashmir Jammu and Kashmir 1,011
Rajasthan West Rajasthan 313
East Rajasthan 675
Madhya Pradesh Madhya Pradesh 1,017
East Madhya Pradesh 1,338
Gujarat Gujarat region 1,107
Saurashtra and Kachchh 578
Goa Konkan and Goa 3,005
Maharashtra Madhya Maharashtra 901
Marathwada 882
Vidarbha 1,034
Andhra Pradesh Coastal Andhra Pradesh 1,094
Rayalaseema 680
Tamilnadu Tamilnadu and Pondicherry 998
Pondicherry Tamilnadu and Pondicherry 998
Karnataka Coastal Karnataka 3,456
North Interior Karnataka 731
South Interior Karnataka 1,126
Kerala Kerala 3,055
Telangana Telangana 961

9th Class Social Studies 4th Lesson Atmosphere InText Questions and Answers

Question 1.
List out some of the ways in which particulates in the atmosphere are beneficial and harmful to us. (Text Book Page No. 37)
1. The fine dust particles present in the atmosphere are called particulates.

2. Particulates may come from natural processes such as sand storms over deserts and natural forest fires and from human activity such as burning forests, burning petroleum and industrial emissions.

3) Benefits of particulates :
a) The particulates can change atmospheric conditions that may be beneficial to life on Earth.
b) The particulates in the atmosphere cause the bright colour of the sunrise or sunset.
c) The particulates help rainfall and hailstones to fall.

4) Harmful effects of particulates :
a) They cause problems by altering temperature and rainfall patterns.
b) They can make it difficult for people to breathe.
c) They can make it difficult for the plants to breathe and photosynthesise.

AP Board Solutions

Question 2.
In which layer is the life present? (Text Book Page No. 39)
In troposphere the life is present. The suitable conditions that make life possible in the troposphere are :

  1. The troposphere is the lower most layer of the atmosphere.
  2. It contains about 75% of the total gaseous mass of the atmosphere and practically all the moisture and dust particles.
  3. The entire weather phenomenon happens in this sphere.
  4. Condensation, evaporation, precipitation, rainfall, cyclones etc., occur in this layer.

Question 3.
About which layer do we have very less knowledge? (Text Book Page No. 39)

  • Exosphere is the upper most layer of the atmosphere.
  • This is the highest layer.
  • Very less is known about it.

AP Board Solutions

Question 4.
Which layer of the atmosphere is ideal for flying jet aircrafts? Why? (Text Book Page No. 39)

  • Stratosphere is ideal for flying jet aircrafts.
  • Because this layer is almost free from clouds and associated weather phenomenon.
  • These conditions are most ideal for flying jet aircrafts in this layer.

Question 5.
Our skin dries up more during winters. Why?

  • Water vapour (i.e., the humidity) is a very important component in the atmosphere.
  • The relative humidity plays a large role in determining our comfort level.
  • If the relative humidity is 100 percent, we feel much hotter than the actual temperature indicates because our skin, sweat does not evaporate at all.
  • If the humidity is low, our skin and mucous membranes are dry.
  • As a result of low humidity, we’ll have chapped lips, dry and itchy skin, and a dry sore throat when we wake up in the morning.
  • Low humidity also dries the plants and furniture.

Question 6.
Observe the following figure and describe from which pressure belt to which pressure belt are the Westerlies, trade winds and polar Easterlies are blowing.
AP Board 9th Class Social Studies Solutions Chapter 4 Atmosphere 4

  • The Westerlies blow from subtropical high pressure belts to sub polar low pressure belts in both the hemispheres.
  • The trade winds blow from sub tropical high pressure belt to equatorial IQW pressure belt.
  • Polar Easterlies blow from polar high pressure belt to polar low pressure belt.

Question 7.
What will happen if water vapour is not present in air?
1. The condensation of water vapour to the liquid or ice phase is responsible for clouds, rain, snow and other precipitations.

If water vapour is not present in the atmosphere, clouds, rains, snow will not occur. If there is no rain, life will not be possible on earth.

2. Water vapour is one of the green house gases. Green house gases play a major role in determining the balance of between the amount of radiation entering the Earth’s surface and the amount of radiation leaving the Earth’s surface.

The green house effect keeps the Earth’s surface about 33°C warmer thair-it would otherwise be.

Question 8.
Why is atmosphere important for us?

  • We breathe in oxygen which is one of the components of atmosphere.
  • We breathe out carbon dioxide, which in turn is taken in by plants in their respiration.
  • The atmosphere prevents harmful rays of the sun from reaching us.
  • The green plants take in carbon dioxide, use sunlight and water to photosynthesise and we get delicious fruits, vegetables, and grains from them.
  • These give us proteins, carbohydrates, sugars, fats, minerals and other nutrients that we need.
  • The atmospheric winds transport water from the oceans deep into the continents in the form of rain.
  • Atmospheric winds erode rocks and are responsible for the formation of many kinds of soils with whose fertility we grow many kinds of crops.
  • Atmosphere helps in cooling monsoon rains.
  • Atmosphere helps in diffusion of perfumes and helps in the travelling of sound waves.
  • Thus we can say atmosphere is important for us.

AP Board Solutions

Question 9.
Can you imagine why life is not possible on the Moon? (Text Book Page No. 37)

  • Life is not possible on the Moon because the Moon has no atmosphere.
  • On Moon we don’t have atmospheric pressure without which we cannot live.
  • Because of lack of atmosphere we don’t have any protection from ultra violet raditation.
  • Because of the lack of magnetosphere, we will be frequently bombarded by the charged particles.
  • There is no water on the Moon which is the first and foremost requirement for the life.
  • For all the above reasons life is not possible on the Moon.

AP Board 9th Class Social Studies Solutions