NCERT Solutions for Class 11 Geography (Fundamental of physical geography) Chapter 10 Water in the Atmosphere

NCERT
SOLUTIONS
CLASS - 11th

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Book : Fundamental of Physical Geography Ncert Solutions | Chapter - 11 Social Science Geography

Class : 11th

Subject : Geography

Chapter : 11

Chapter Name : Water in the Atmosphere

Q1 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 particle

(d) Oxygen

(ii) Which one of the following process is responsible for transforming liquid into vapour?

(a) Condensation

(b) Transpiration

(c) Evaporation

(d) Precipitation

(iii) The air that contains moisture to its full capacity :

(a) Relative humidity

(b) Specific humidity

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Book : Fundamental of Physical Geography Ncert Solutions | Chapter - 11 Social Science Geography

(c) Absolute humidity

(d) Saturated air

(iv) Which one of the following is the highest cloud in the sky?

(a) Cirrus

(b) Stratus

(c) Nimbus

(d) Cumulus

Answer.(i) (d) Oxygen

(ii) (c) Evaporation

(iii) (a) Relative humidity

(iv) (a) Cirrus

Page : 98 , Block Name : Multiple Choice Questions

Q2 Answer the following questions in about 30 words.

(i) Name the three types of precipitation.

(ii) Explain relative humidity.

(iii) Why does the amount of water vapour decreases rapidly with altitude?

(iv) How are clouds formed? Classify them.

Answer.

(i) The three types of precipitation are :-

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Book : Fundamental of Physical Geography Ncert Solutions | Chapter - 11 Social Science Geography

➔​ ​Rainfall

➔​ ​Snowfall

➔​ ​Hailstorms and Sleet

(ii) Relative humidity is the percentage of absolute humidity compared to the full capacity to its
full capacity at a given temperature is known as relative humidity.

(iii) The amount of water vapour in the air depends upon the rate of evaporation and
temperature of the air which determines the holding capacity of water vapour of the air.Since
both temperature and evaporation decreases with altitude and as a result water vapour also
decreases rapidly with altitude.

(iv) Clouds are a collection of water droplets or tiny crystals of ice. These water droplets or tiny
crystals of ice are formed by the condensation of water vapour in free air at elevations. . Since
clouds are elevated, they form different shapes. They vary in height, expanse, density and
opaqueness.They can be broadly classified as-

➔​ ​Cirrus :- Formed at high altitudes ranging between 8,000 - 12,000m

➔​ ​Cumulus :- Formed at a height of 4,000 - 7,000 m.

➔​ ​Stratus :- These are layered clouds covering large portions of the sky. Formed either
due to loss of heat or the mixing of air masses with different temperatures.

➔​ ​Nimbus :- Formed at middle levels or very near to the surface of the earth.

Page : 98 , Block Name : Short Answer Question

Q3 Answer the following questions in about 150 words.

(i) Discuss the salient features of the world distribution of precipitation.

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

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Book : Fundamental of Physical Geography Ncert Solutions | Chapter - 11 Social Science Geography

Answer.

(i) After condensation of water vapour, the release of moisture is called precipitation.
Precipitation in the form of water is called rainfall and in solid form can be as snowfall, hail or
sleet. The distribution of rainfall throughout the world is different is varied. The salient features
are as follows-

➔​ ​Rainfall steadily decreases towards the poles.

➔​ ​It is relatively more concentrated in the coastal areas of the world than the interior of
the continents.

➔​ ​Rainfall is more in the areas where there is great source of water. Thus, it is more
over the oceans than on the landmasses of the world.

➔​ ​Between 35​0​ and 40​0​ N and S of the equator, the rain is heavier on the eastern
coasts and decreases towards the west.

➔​ ​Between 45​0​ and 65​0​ N and S of the equator, rainfall is received on the western
regions of the continents first and decreases toward the east.

➔​ ​Wherever mountains run parallel to the coast, the rain is greater on the coastal plain,
on the windward side and it decreases towards the leeward side.

(ii) Water Vapour in the atmosphere takes up the moisture in the atmosphere to form the
following which forms of condensation :-

➔​ ​Dew

➔​ ​Frost

➔​ ​Fog and mist

➔​ ​Clouds

Dew

Dew is a form of condensation. Condensation takes place when the moist air comes in contact
with colder objects other than the hygroscopic condensation nuclei. Condensation depends
upon the temperature and location. When moisture in the form of water droplets are deposited
on cooler surfaces of solid objects like stones, leaves etc. Dew mostly forms when there is a

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Book : Fundamental of Physical Geography Ncert Solutions | Chapter - 11 Social Science Geography

clear sky, calm air, high relative humidity and cold nights. It is essential for the formation of dew
that the dew point is above the freezing point.

Frost

When the dew point is at or below the freezing point and condensation takes place below
freezing point, then frost forms on cold surfaces. The moisture is deposited not as water
droplets but as ice crystals. The ideal condition for formation of frost is same as that of dew
except that the air temperature must be at or below the freezing point.

Page : 98 , Block Name : Long Answer Question

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