Page 67 - Science class 4

8 Air, Water and Weather

l More about Air, Water and Water-cycle
l More about Air, Water and Water-cycleMore about Air, Water and Water-cycle
l Evaporation, Condensation, Water CycleEvaporation, Condensation, Water Cycle
l Evaporation, Condensation, Water Cycle
Inside
Inside l Purification of Water
l Purification of WaterPurification of Water
the l Boiling, Sedimentation, Filtration, Chlorination.
the
l Boiling, Sedimentation, Filtration, Chlorination.Boiling, Sedimentation, Filtration, Chlorination.
Chapter
Chapter
l Uses of WaterUses of Water
l Uses of Water
l WeatherWeather
l Weather
l Role of the Sun
l Role of the Sun Role of the Sun
Air is all around us. It is a mixture of several

gases. It contains water vapour and dust. The
Earth is surrounded by a blanket of air which is

called the atmosphere .

We can feel air when it blows. Moving air is

called wind . A gentle wind is called breeze and a
strong wind is called gale . Very strong winds are

called windstorms . If they are accompanied

with thunder and lightning, they are called thunderstorms . Wind affects the

weather of a place.

Sea and Land Breezesand Land Breezesand Land Breezes
Sea
Sea
Land can heat up and cool down
faster than the water and this gives
Rising warm air Descending
Rising warm air
Rising warm air
Descending
Descending
cool air
cool air rise to sea breeze and land breeze
cool air
especially in the coastal areas.
Sea breeze
Sea breeze
Sea breeze
At the day time, land gets heated up
Land
Land
Land by the heat of the Sun. The air above
Ocean
Ocean
Ocean
the land is then also heated up. The
hot air rises up from the land and the
cool air from the sea flows in, to take
Land breeze blows in the evening. its place. This is known as sea breeze .