Geography ch 5 - Precipitation — Social Studies STD 9 — Question

Precipitation means water falls in the solid or liquid state from the clouds to the earth surface. Snow, hailstorms, rainfall are the major forms of precipitation.

(i) Snow:
Answer:

• When the temperature in the atmosphere falls below the freezing point the water vapour directly turns into snowflakes. This is called sublimation.
• Hence the vapour in the form of gas transform into solid snow. Precipitation in the form of solid particles is known as snowfall.

As snow is in the solid form. It does not run like water and layers of the snow get deposited on the top of the others and when the snow melts the region gets fresh water.

(ii) Hail:

• When there is lot of heat on the earth’s surface, the upward air flow blows at a greater speed. Because of this upward flow, the temperature of air reduces and the condensation of the water vapour takes place, and dark clouds are formed.
• Because of the upward movement of the air, these water droplets go at higher altitude and solidify forming hailstones.
• As the hailstones are heavy, they fall toward the earth’s surface because of gravity. The crops may get destroyed and loss of life and property may occur.
• Hailstones occurs in summer in India, Africa and in some parts of south east Asia.

(iii) Rainfall:

• We get water generally in the form of rainfall. The temperature of the air with water vapour reduces when it goes higher and condensation of the vapour occurs.
• Clouds formed with the condensed water droplets and dust particles accumulate.
• As these water droplets increase in the size, they cannot float in the air anymore because of their weight. They come down as rainfall
• The different types of rainfall are: Convectional rainfall, Orographic rainfall and Cyclonic rainfall.

(iv) Fog, dew and frost:

• • When the condensation or solidification of the water vapour in the atmosphere occurs near the earth’s surface, it leads to the formation of fog, dew and frost.