Page 137 - Health, Population and Environment Education 9

iii. Determinant of climate
Air is one of the major factors to determine the climate of a place. Air which contains
water vapour causes rain fall whereas the dry air which does not contain water vapour
does not cause rain. So the climate is humid or arid depending on the nature of air.

iv. Pollination

Air is important means for pollination in plants. Plants yield fruits and seed when
pollination takes place by means of air.

v. Photosynthesis

Plants need carbon dioxide to prepare their food by photosynthesis.
vi. Winnowing

Air is needed to separate the grains from their cover and other unnecessary things.

Fig: 6
Pollination Winnowing

Water
Water is the compound formed by combination of hydrogen and oxygen. It is one of the
important resources found in nature. It has occupied around two third of the total area of
the earth. Even our body has contained more than 70% of water. Of total water found in
the world,only around 3% is fresh and drinkable. Remaining 97% contains salt and is not
safe for drinking. Oceans, seas, rivers, ponds, lakes, streams, waterfalls, wetlands are the
various sources of water. Nepal is said to be second richest country in the world in terms
of water resources after Brazil. The water resources are classified into surface water and
underground water.

Fig: 7
Ocean River Lake

GREEN Environment Population and Health Education Book-9 137