3. Humidity and clouds / Class 8. Geography

Class 8 Geography
3. Humidity and clouds
1. Match the column and the chain

2. Choose the correct word from the brackets and complete the sentences:
(Options: Cumulonimbus, relative humidity, absolute humidity, condensation, vapor-holding capacity)

1. The ………….. of the air is dependent on the temperature of the air.
Answer: vapour-holding capacity
2.The amount of vapour in 1 cu.m, of air shows the ………….
Answer: absolute humidity
3.As …………. is less in the desert areas, the air is dry there.
Answer: relative humidity
4. ……………. type of clouds are indicators of the storm.
Answer: Cumulonimbus
5. In a free environment, the ………….. of the vapour present in the atmosphere takes place around the dust particles.
Answer: condensation

Q. 3. Differentiate between: 
1. Humidity and clouds:

2.Relative Himidity and absolute humidity

3. Cumulus clouds and cumulusnimbus humidity

Q 4. Answer the following questions:

 (a) Why is the air in a region dry? 

Ans: If the amount of humidity in the air is less then the air in a region will be dry.

 (b) How is humidity measured? 

Ans:  The humidity is measured in gram per cubic meter.

 (c) What are the prerequisites for

condensation? 

Ans:

✔ The process of changing of water vapour in the air into water is called condensation.

If the temperature of the air reduces, its vapour holding capacity also reduces. 

✔When relative humidity of the air becomes 100%, vapour starts condensing.

 ✔At this time, the temperature of the 

air should be at dewpoint. 

✔In the free environment, condensation of the vapour in the air occurs around fine particles (dust, salt, etc.)

 (d) What is a cloud? Write its types. 

Ans: Clouds are a form of condensation at 

higher elevation. 

Types of Clouds: 1. High Clouds 2. Medium Clouds 3. Lower clouds

 (e) Which type of clouds give rain? 

Ans: Nimbostratus and cumulonimbus clouds give rain.

 (f) On what does the percentage of

relative humidity depend?

Ans:  The percentage of relative humidity depend on absolute humidity and the moisture holding capacity of air at a temperature. 

Q 5. Give geographical reasons: 

 (a) Clouds float in the sky.

Ans:  At a greater altitude the condensed fine particles of water and ice are weightless and because of vertical flow of air the clouda float in the sky

 (b) The proportion of relative humidity 

changes according to altitude.

Ans: 

✔The amount of water vapour changes 

according to difference in temperature. 

✔Similarly, relative humidity also changes. 

✔Generally, relative humidity is more in the 

mornings and nights.

✔ In the afternoon, as temperature increases, relative humidity decreases. 

✔Near coastal areas, the relative humidity is more and so the air is moist . 

✔Indesert areas, relative humidity is less.

 (c) Air becomes saturated. 

Ans:At a certain temperature, the moisture 

holding capacity of air becomes equal to the 

proportion of moisture present in it. This 

condition of the air is called saturation of the air.

 (d) Cumulus clouds change into 

cumulonimbus clouds. 

Ans: 

✔These clouds are formed extensively from 500 m to 6000 m altitude.

 ✔The vertical flow of the air adds to the formation of these clouds. 

✔These are huge and dome-shaped. 

 ✔The vertical expanse of these clouds increases so much that they turn into cumulonimbus clouds and bring rain.

Q 6. Solve the following: 

 (a) When the temperature of the air is 30° C, its vapour-holding capacity is 30.37 

gms/ cu.m. If absolute humidity is 18 

gms / cu.m. then what would be the 

relative humidity? 

Ans: (soon the answer will be updated)

 (b) What would be the absolute humidity of 

air if 1 cu.m. air contains 4.08 gms of 

vapour at 0°C temperature? 

Ans: (soon the answer will be updated)