class 7 geography
NCERT Solutions for Class 7 Geography Social Science Chapter 4 Air | SOLUTION FOR AIR . | YASH SINGHAL
Q1. What is
atmosphere?
Ans . Our earth is surrounded by a huge blanket of air called atmosphere.
Q2. What is the instrument that measures the amount of
rainfall?
Ans. Rain Gauge
Q3. What is the
instrument that measures the atmospheric pressure?
Ans. Barometre
.
Q4. What is the wind vane used for?
Ans. Wind Vane
shows the direction of the wind.
Q5. Which layer of the
atmosphere makes radio communication possible?
Ans. Ionosphere.
Q6. What is the standard unit of measurement for
temperature?
Ans. The
standard unit of measuring temperature is degree Celsius.
Q7. Who invented the celsius scale of temperature?
Ans. It was invented by Anders Celsius.
Q8. Which gas protects
us from harmful sun rays?
Ans. Ozone protects us from the harmful effect of the sun rays.
Q9. Which layer of the
atmosphere is free from clouds?
Ans.
Stratosphere layer is almost free from Clouds.
Q10. What is air pressure?
Ans. Air pressure is defined as the
pressure exerted by the weight of air on the earth’s surface.
GIVE REASONS :-
Q1. Why wet clothes
take longer time to dry on a humid day?
Ans. Wet
clothes take longer time to dry on a humid day because the air has a plenty of
water vapor already present in it and is not able to accommodate more water
vapor.
Q2. Why amount of insolation decreases from equator
towards poles?
Ans. Sun rays falls almost vertically on the equator and covers less space
whereas sun rays falls at slanting angle on the poles and covers more space.
Thus, the amount of insolation decreases from the equator towards the poles.
Q1. How does carbon dioxide create greenhouse effect?
Ans. Carbon dioxide released in the atmosphere creates a greenhouse effect by trapping the heat radiated from the earth.
Q2. Name three types
of rainfall.
Ans. On the basis of mechanism, there are three types of rainfall: the convectional rainfall, the orographic rainfall and the cyclonic rainfall.
Q3. What are the different types of winds?
Ans.
Winds can be broadly divided into three types.
1.Permanent winds – The trade winds, westerlies and easterlies are the permanent winds. These blow constantly throughout the year in a particular direction.
2.Seasonal winds – These winds change their direction in different seasons. For example: monsoons in India.
3.Local winds – These blow only during a particular period of the day or year in a small area. For example: land and sea breeze and loo.
Q4. Which two gases make the bulk of the atmosphere?
Ans. Nitrogen and oxygen are two gases which make up the bulk of the atmosphere.
Q5. Which gas creates greenhouse effect in the atmosphere?
Ans. Carbon dioxide released in the atmosphere creates a greenhouse effect in the atmosphere.
Q6. What is the weather?
Ans. The hour to hour or the day to day condition of the atmosphere is called weather. Weather can change dramatically from day-to-day. It may be classified as hot, dry, cold or wet.
Q1. Write a short note on the distribution of air pressure in atmosphere?
Ans. Air pressure is defined as the pressure exerted by the weight of air on the earth’s surface. As we go up the layers of atmosphere, the pressure falls rapidly. The air pressure is highest at sea level and decreases with height. Horizontally the distribution of air pressure is influenced by temperature of air at a given place.
Q2.
Write a short note
on different layers of atmosphere.
Ans. Our atmosphere is divided into five layers starting from the earth’s surface :
Troposphere: This layer is the most important layer of the atmosphere. Its average height is 13 km. The air we breathe exists here.
Stratosphere: Above the troposphere lies the stratosphere. It extends up to a height of 50 km. This layer is almost free from clouds and associated weather phenomenon, making conditions most ideal for flying aeroplanes.
Mesosphere: This is the third layer of the atmosphere. It lies above the stratosphere. It extends up to the height of 80 km. Meteorites burn up in this layer on entering from the space.
Thermosphere: In thermosphere temperature rises very rapidly with increasing height. Ionosphere is a part of this layer. It extends between 80 400 km. This layer helps in radio transmission.
Exosphere: The upper most layer of the atmosphere is known as exosphere. This layer has very thin air. Light gases like helium and hydrogen float into the space from here.
1. Which of the following gases protects us from harmful sun rays?
(a) Carbon dioxide
(b) Nitrogen
(c) Ozone
Answer: c
2. The most important layer of the
atmosphere is
(a) Troposphere
(b) Thermosphere
(c) Mesosphere
Answer: a
3. Which of the following layers of the atmosphere is free from clouds?
(a) Troposphere
(b) Stratosphere
(c) Mesosphere
Answer: b
4. As we go up the layers of the atmosphere,
the pressure
(a) Increases
(b) Decreases
(c) Remains the same
Answer: b
5. When precipitation comes down to the earth in the liquid form, it is called
(a) Cloud
(b) Rain
(c) Snow
Answer: b
Short questions answer:
Q1. How does carbon dioxide create greenhouse effect?
Ans. Carbon dioxide released in the atmosphere creates a greenhouse effect by trapping the heat radiated from the earth.
Ans. On the basis of mechanism, there are three types of rainfall: the convectional rainfall, the orographic rainfall and the cyclonic rainfall.
Q3. What are the different types of winds?
Ans.
Winds can be broadly divided into three types.
1.Permanent winds – The trade winds, westerlies and easterlies are the permanent winds. These blow constantly throughout the year in a particular direction.
2.Seasonal winds – These winds change their direction in different seasons. For example: monsoons in India.
3.Local winds – These blow only during a particular period of the day or year in a small area. For example: land and sea breeze and loo.
Q4. Which two gases make the bulk of the atmosphere?
Ans. Nitrogen and oxygen are two gases which make up the bulk of the atmosphere.
Q5. Which gas creates greenhouse effect in the atmosphere?
Ans. Carbon dioxide released in the atmosphere creates a greenhouse effect in the atmosphere.
Ans. The hour to hour or the day to day condition of the atmosphere is called weather. Weather can change dramatically from day-to-day. It may be classified as hot, dry, cold or wet.
Long questions answer :
Q1. Write a short note on the distribution of air pressure in atmosphere?
Ans. Air pressure is defined as the pressure exerted by the weight of air on the earth’s surface. As we go up the layers of atmosphere, the pressure falls rapidly. The air pressure is highest at sea level and decreases with height. Horizontally the distribution of air pressure is influenced by temperature of air at a given place.
Ans. Our atmosphere is divided into five layers starting from the earth’s surface :
Troposphere: This layer is the most important layer of the atmosphere. Its average height is 13 km. The air we breathe exists here.
Stratosphere: Above the troposphere lies the stratosphere. It extends up to a height of 50 km. This layer is almost free from clouds and associated weather phenomenon, making conditions most ideal for flying aeroplanes.
Mesosphere: This is the third layer of the atmosphere. It lies above the stratosphere. It extends up to the height of 80 km. Meteorites burn up in this layer on entering from the space.
Thermosphere: In thermosphere temperature rises very rapidly with increasing height. Ionosphere is a part of this layer. It extends between 80 400 km. This layer helps in radio transmission.
Exosphere: The upper most layer of the atmosphere is known as exosphere. This layer has very thin air. Light gases like helium and hydrogen float into the space from here.
M.C.Q
(Multiple choise question)
1. Which of the following gases protects us from harmful sun rays?
(a) Carbon dioxide
(b) Nitrogen
(c) Ozone
Answer: c
(a) Troposphere
(b) Thermosphere
(c) Mesosphere
Answer: a
3. Which of the following layers of the atmosphere is free from clouds?
(a) Troposphere
(b) Stratosphere
(c) Mesosphere
Answer: b
(a) Increases
(b) Decreases
(c) Remains the same
Answer: b
5. When precipitation comes down to the earth in the liquid form, it is called
(a) Cloud
(b) Rain
(c) Snow
Answer: b
Match the following :
(i) Trade
Winds
|
(a) Incoming
solar energy
|
(ii) Loo
|
(b) Seasonal
wind
|
(iii)
Monsoon
|
(c) The
horizontal movement of Air
|
(iv) Wind
|
(d) A layer
of ozone gas
|
(e)
Permanent wind
|
|
(f) Local
wind
|
