Page 77 - ACTIVE SCIENCE 4 TOC

Land Breeze
High
At night, land cools down more Pressure
quickly than the sea, cooling

the air above the land. The air Land Breeze
above the sea is warmer and

rises up. The cool air blows from Low
land towards the sea to take its Land cools down Pressure
place. Therefore, the wind that at night The sea water is

blows from land towards the sea warm at night
at night is called land breeze.

Land Breeze
Let’s Recapitulate

Fill in the blanks.
1. The earth moves on its own axis. It is called ______________.

2. The earth moves around the sun in its own orbit. It is called ______________.
3. The earth takes ______________ to complete one revolution.

4. The wind which blows from sea towards land during the day is called ______________.

Water

Water is a necessity for our survival. It is the primary requirement of our life. Most

of our body weight is made up of water. About 3/4 part of the earth is covered with
th
water. All the living beings need water to live. There are three forms of water – ice,
water and water vapour. We not only find water in oceans, rivers, sea; it is also

found under the ground. Let us read in detail.

Evaporation
The process in which water changes into water vapour on heating is called

evaporation. More water gets evaporated when the weather is hot. The amount
of water vapour present in the atmosphere is called humidity.

Condensation

When water vapour changes into water due to cooling, it is
called condensation. Forms of water like fog, dew, frost,

hail and snow are all occur due to condensation. When a
glass of cold water is placed in the open, we see tiny water

84 Active Science-4