Page 78 - ACTIVE SCIENCE 4 TOC

droplets on its outside. The water vapour in the atmosphere comes in contact with
the cool glass and condenses to form water droplets.

Likewise, fog is a thick layer of clouds made of tiny drops of water. Dew can be

seen in the early morning during winters in the form of tiny drops of water on
grass and leaves. Frost is seen when water freezes into tiny white crystals. Hail

is formed when the freezing raindrops pass through a very cold region. Snow is
formed when water vapour freezes into white snowflakes.

Activity 9.1

Aim : Observing evaporation and condensation.

Materials Required : A cotton cloth, a glass of cold juice.

Procedure : 1. Wash a handkerchief and keep it out under sunlight.

2. Also fill a glass of cold juice and keep it aside.

3. Observe both the things after an hour.

Observation : You will find that the cloth has dried up. You will also find tiny

droplets of water on the outer surface of the glass.

Conclusion : The water in the cloth has evaporated due to the heat of the sun.
In case of the glass, the water vapour present in the air condensed

on the outer surface of the glass and so, tiny water droplets were seen.

Water Cycle

The water of lakes and rivers

changes into water vapour
due to the sun’s heat. This
water vapour rises up in the Rain & Snow

atmosphere and cools down
into tiny drops of water. These
drops combine together and Evaporation

make clouds. On becoming
heavy, the clouds fall on Ground Water
earth as rain or snow. This

continuous circulation of
water in the air and on the Water cycle Water table

earth is called water cycle.

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