How The Rain Falls Hydrologic Cycle of Nature
Lets take a look at the hydrologic cycle of nature. The heat of the sun, rotation and revolution of the earth, unevenness of the surface of the earth and the presence of masses of water in contrast to land cause variations in atmospheric vapour from which rainfall is derived. Evaporation from free water surfaces like oceans, lakes, rivers swamps, from moist soil surfaces and from transpiration by plants causes the water vapour to rise and move towards low pressure areas and then, after cooling, to drop in the form of rain. A part of water vapour falls as rain on the very surfaces from which evaporation takes place and a part goes elsewhere.
The precipitation on land is either disposed of as surface flow by the streams and is taken to the seas or is partly utilized and transpired by plants and partly seeps into the ground to replenish the ground water from which again some part evaporates and some flows into the oceans. The surface water of the rivers ultimately goes back to the ocean.