Air Extra Questions Chapter 4 Class 7 Geography
Chapter 4 Air Class 7 Geography Extra Questions is very helpful in scoring good marks in the exams and covering all the important topics inside the chapter. Extra Questions for Class 7 will improve your learning experience and answering any question with ease.
Chapter 4 Air Very Short Answer Questions (VSAQs):
1. Which among the following sphere suitable for flying aeroplanes.
Answer
Stratosphere.
2. The amount of ______ decreases from the equator towards the pole.
Answer
Temperature.
3. Green plants use ______ to make their food.
Answer
Carbon dioxide.
4. Those wind which blow only during a particular period of the day or year in a small area is called _______.
Answer
Seasonal winds.
5. What is photosynthesis?
Answer
Photosynthesis is the process by which green plants and some other organisms use sunlight to synthesise nutrients from carbon dioxide and water.
6. What happens when air is heated?
Answer
When air is heated, it expands and becomes lighter and goes up. Cold air is denser and heavy.
7. What happens when trees on hill sides are cut?
Answer
When trees on hill sides are cut, rainwater flows down the bare mountains and can cause floodings of low lying areas.
8. Which atmospheric layer has very thin air and light gases?
Answer
Exosphere layer has very thin air and light gases like helium and hydrogen float into the space from here.
9. What is humidity?
Answer
Moisture in the air at any time, is known as humidity.
10. What is the use of Barometer?
Answer
Atmospheric pressure is measured by Barometer.
11. Mention one feature of seasonal winds?
Answer
Seasonal winds change their direction in different seasons.
12. Divide rainfall on the basis of mechanism.
Answer
On the basis of mechanism, there are three types of rainfall— the conventional rainfall, the orographic rainfall and the cyclonic rainfall.
Chapter 4 Air Short Answer Questions (SAQs):
1. Mention the main features of Stratosphere?
Answer
The features of the stratospheres
• It lies above the troposphere and 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.
2. What do you mean by air circulation?
Answer
When air is heated it becomes lighter and goes up. Cold air is denser and heavy that is why it tends to sink down. When hot air rises, cold air from surrounding area rushes there to fill the gap. This is how air circulation takes place.
3. Define low and high pressure.
Answer
In areas where temperature is high the air gets heated and rises. This creates a low pressure area.In the area having low temperature the air is cold. It is therefore heavy. Heavy air sinks and creates a high pressure.
4. Define the term relative humidity.
Answer
The ratio between actual amount of water vapour present in the air at a given temperature and the maximum amount of water vapour that the atmosphere can retain at that temperature is known as relative humidity.
5. What do you mean by global warming?
Answer
Carbon dioxide released in the atmosphere creates a greenhouse effect by trapping the heat radiated from the earth. Without it the earth would have been too cold to live in. But when its level in the atmosphere increases due to factory smoke or car fumes, the heat retained increases the temperature of the earth. This is called global warming.
6. Describe the composition of atmosphere.
Answer
The atmosphere consists of mixture of gases having a relatively uniform composition in the lower layer. An average sample of pure dry air consist of nitrogen(78 %),oxygen (21%) and argon(0.9 %),other gases such as carbon dioxide, hydrogen helium and ozone are present in minute quantities. The lower layer of atmosphere also contains water vapour in variable quantities.
7. What is precipitation? Mention its different forms.
Answer
When the water vapour in the atmosphere rises, it starts cooling. The water vapour condenses causing formation of droplets of water. When these droplets of water become too heavy to float in air, then they come down as precipitation.
Precipitation that comes down to the earth in liquid form is called rain. Other forms of precipitation are snow, sleet and hail.
8. Differentiate between weather and climate.
Answer
• Weather is hour-to-hour, day-to-day condition of the atmosphere. Climate is the average overall weather condition of a place for a longer period of time.
• The change of weather is a continuous phenomenon. But the climate of a place remains more or less the same year after year.
Chapter 4 Air Long Answer Questions (LAQs):
1. What is air pressure? Mention four important points associated with air pressure.
Answer
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.
• In areas where temperature is high, the air gets heated and rises. This creates a low-pressure area. Low pressure is associated with cloudy skies and wet weather.
• In areas having lower temperature, the air is cold. It is therefore heavy. Heavy air sinks and creates a high pressure area. High pressure is associated with clear and sunny skies.
2. What is rain? Mention three types of rainfall. How is rainfall important for plants and animals?
Answer
Condensation of water vapour causes formation of small drops of water. When these droplets of water join together, they grow in size and become too heavy to float in air. Then they fall down as rain drops.
There are three types of rainfall:
• the convectional rainfall
• the orographic rainfall, and
• the cyclonic rainfall.
Rainfall is important for the survival of plants and animals. It brings freshwater to the earth’s surface. It makes the soil ready for cultivation. Farmers depend on rainfall for their agricultural activities. If rainfall is less, water scarcity and drought occur. Hence, sufficient rainfall is essential.
3. What is wind? Describe its different types.
Answer
The horizontal movement in air along the surface of the earth is called wind. It always blows from high pressure areas to low pressure areas. The wind is named after the direction from which it blows, for example, the wind blowing from the west is called westerly. Winds can be broadly divided into three
types:
• Permanent winds: These blow constantly throughout the year in a particular direction. The trade winds, westerlies and easterlies are the permanent winds.
• Seasonal winds: These winds change their direction in different seasons. For example monsoon in India.
• Local winds: These winds blow only during a particular period of the day or year in a small area. They may last for a short period. For example, land and sea breeze. These winds have local names. Loo is one such wind which is a very hot dry and dusty and blows in the northern plains of India.