NCERT Solutions Class-11 Geography Chapter-10: Water in the Atmosphere

Conclusion

Exercises Page No: 78

Que 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 particle

(d) Oxygen

Answer:

(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

Answer:

(c) Evaporation

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

(a) Relative humidity

(b) Specific humidity

(c) Absolute humidity

(d) Saturated air

Answer:

(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 :

(a) Cirrus

2. Answer the following questions in about 30 words.

(i) Name the three types of precipitation.

Answer:

The three types of precipitation are:

• Rainfall: Precipitation in the form of water droplets falling from clouds.

• Snowfall: Precipitation in the form of delicate flakes of snow.

• Hailstones: Occasionally, raindrops freeze into small, round ice pellets before reaching the ground, forming hailstones.

(ii) Explain relative humidity.

Answer:

The percentage of moisture in the atmosphere compared to its maximum capacity at a specific temperature is called relative humidity.

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

Answer:

Water vapor concentration is higher over oceans and lower over continents due to the absence of large water bodies. At higher altitudes, where there are no significant water bodies, temperature decreases, leading to reduced rates of evaporation and a rapid decrease in water vapor concentration.

(iv) How are clouds formed? Classify them.

Answer:

A cloud is a collection of tiny water droplets or ice crystals formed by the condensation of water vapor in the atmosphere at high altitudes. Clouds are classified into four types based on their height, size, density, and transparency:

Cirrus

Cumulus

Stratus

Nimbus

3. Answer the following questions in about 150 words.

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

Answer:

Different regions of the Earth receive varying amounts of rainfall throughout the year and across different seasons.

Rainfall decreases from the equator towards the poles.
Coastal areas generally experience higher rainfall compared to inland regions due to proximity to large bodies of water.
Oceans receive more rainfall than landmasses because they are significant sources of moisture.
Between latitudes 35° and 40° N and S, eastern coasts receive heavier rainfall, decreasing towards the west.
Between latitudes 45° and 65° N and S, rainfall is first received on western margins of continents due to westerlies, decreasing towards the east.
Where mountains run parallel to the coast, coastal plains experience higher rainfall on the windward side and less on the leeward side.

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

Answer:

Condensation is the process where water vapor turns into water droplets due to a decrease in temperature. It occurs when warm air containing moisture comes into contact with a cooler surface or air, causing the moisture to condense.

Forms of condensation include dew, frost, fog, and clouds.

Dew forms when water vapor condenses into water droplets on cooler surfaces like grass, leaves, or stones. It requires clear skies, calm air, high humidity, and cold temperatures, typically during long, cold nights.

Frost occurs when condensation happens below freezing point, resulting in the formation of ice crystals instead of water droplets. Ideal conditions for frost formation are similar to those for dew, but the air temperature must be at or below freezing point for white frost to form.