World Water Balance:Total quantity of water in the world is estimated to be about 1386 million cubic
kilometer (M Km3). About 96.5% of this water is contained in the oceans as saline
water. Some of the water on the land amounting to about 1% of the total water is
also saline. Thus, only about 35.0 M Km 3 of fresh water is available. Out of this
about 10.6 M Km3 is both liquid and fresh and the remaining 24.4 M Km 3 is
contained in frozen state as ice in the polar regions and on mountain tops and
The term “precipitation” denotes all forms of water that reach the earth from the
atmosphere. The usual forms are rainfall, snowfall, hail, frost and dew.
The magnitude of precipitation varies with time and space. For precipitation to
form: (i) the atmosphere must have moisture, (ii) there must be sufficient nuclei
present to aid condensation , (iii) weather conditions must be good for
condensation of water vapour to take place, and (iv) the products of condensation
must reach the earth.
FORMS OF PRECIPITATION:
Some of the common forms of precipitation are rain, snow, drizzle, glaze, sleet and