# NCERT Solutions for Class 11 Geography Chapter 11 Water in the Atmosphere

Detailed, Step-by-Step NCERT Solutions for Class 11 Geography Chapter 11 Water in the Atmosphere Questions and Answers were solved by Expert Teachers as per NCERT (CBSE) Book guidelines covering each topic in chapter to ensure complete preparation.

## Water in the Atmosphere NCERT Solutions for Class 11 Geography Chapter 11

### Water in the Atmosphere Questions and Answers Class 11 Geography Chapter 11

Question 1.
Multiple Choice Questions :
(i) Which one of the following is the most important constituent of the atmosphere for human beings?
(a) Water vapour
(b) Nitrogen
(c) Dust particles
(d) Oxygen
(a) Water vapour.

(ii) Which one of the following process is responsible for transforming liquid into vapour?
(a) Condensation
(b) Transpiration
(c) Evaporation
(d) Precipitation
(c) Evaporation.

(iii) The air that contains moisture to its full capacity :
(a) Relative humidity
(b) Specific humidity
(c) Absolute humidity
(d) Saturated air
(d) Saturated air.

(iv) Which one of the following is the highest cloud in the sky?
(a) Cirrus
(b) Stratus
(c) Nimbus
(d) Cumulus
(a) Cirrus.

Question 2.
Answer the following questions in about 30 words each :

(i) Name the three types of precipitation.
Precipitation occurs in three ways :

• Convectional precipitation,
• Orographic precipitation,
• Cyclonic precipitation.

(ii) Explain relative humidity.
Relative humidity : The percentage of moisture present in the atmosphere as compared to its full capacity is known as relative humidity.

The amount of water vapour in the air compared with the amount that would be present if the air was saturated at that temperature. It is expressed in percentage determined by dividing the absolute humidity by water holding capacity of air.

If the air is saturated, its relative humidity is 100%; if only half saturated, the relative humidity is 50%. Since the capacity of air for absorbing and retaining moisture varies with temperature, the relative humidity of air mass can be altered by merely lowering its temperature without changing the actual amount of moisture present in it.

(ii) Why does the amount of water vapour decrease rapidly with altitude?
Water vapour in the atmosphere is the result of evaporation of water from the earth’s surface, a continual process dependent on air. Since the air becomes thinner with altitude, so also does the water vapour.

(iv) How are clouds formed? Classify them.
Clouds are formed by the condensation of water vapour around nuclei of minute dust particles in the air. In most cases, clouds consist of tiny droplets of water, but they may also consist of ice particles if temperature is below freezing point. Most clouds are formed by the rising warm and moist air. The ascending air expands and cools until the dew point is reached and some of the moisture condenses into clouds.
The clouds are of three types :

• High clouds : Cirrus, cirrostratus, cirrocumulus.
• Middle clouds : Altostratus, altocumulus.
• Low clouds: Stratocumulus, stratus, nimbostratus, cumulus and cumulonimbus.

Question 3.
Answer the following questions in about 150 words each :
(i) Discuss the salient features of the world distribution of precipitation.
Different places on the earth’s surface receive different amount of rainfall. As we proceed from the equator towards the poles, rainfall goes on decreasing. The coastal areas of the world receive greater amount of rainfall than the interior regions of the continents.

On the basis of the total amount of annual precipitation major precipitation regimes of the world are as follows :

(i) The equatorial belt, the windward slopes of the mountains along the western coasts in the cool temperate zone and the central areas of the monsoon lands, receive heavy precipitation of over 200 centimetres per annum.

(ii) Areas adjacent to high precipitation region receive moderate rainfall varying from 100-200 cm. per annum. The coastal area in the warm temperate zone also receive moderate amount of rainfall.

(iii) The central parts of the tropical lands and the center and interior parts of the temperate lands receive inadequate precipitation varying between 50-100 cm. per annum.

(iv) Areas lying in the rain shadow regions. The interior of the continents and high latitudes receive low precipitation of less than 50 cm. per annum. The western margin of the continents in the tropical lands, and the arid deserts come under this category.

(ii) What are forms of condensation? Describe the process of dew and frost formation.