An ocean is a large area of saltwater between continents. About 97% of the water on the earth is found in oceans. 2% is in the form of frozen glaciers and ice-caps. The water that snow or rain bring to different regions of the earth goes back to the oceans sooner or later. The snow melts and flows down as streams and rivers. Most of the rivers fall in seas, lakes, and oceans.
The lakes and ponds are filled with rainwater. Some of the rainwater is absorbed by the soil. This water is lost in the process of evaporation and transpiration. The groundwater is the source for many open wells, handpumps, tube wells, and lakes.
The water cycle is an important phenomenon of returning water back to the oceans. The water from the oceans evaporates. This evaporated water condenses and falls back as rain. The water that falls on land flows into the rivers and ultimately falls into the oceans.
A single drop of water spends about 3,230 years in the oceans before entering the water cycle. The circulation of water between the ocean and land occurs continuously and maintains the supply of water on land.
How is Water Returned Back to the Oceans?
Water cycle is the major source of returning water back to the oceans. The process occurs in the following ways:
- The water cycle begins in the oceans.
- The sun heats the water in the oceans. The water evaporates as water vapour into the air. The ice and snow sublimate directly into vapour.
- The evaporated water from the oceans along with the water transpired from the plants rises up in the atmosphere with the air currents.
- These vapours condense into clouds that move around the globe by air currents.
- The particles of the cloud grow, collide and fall out the of the sky as precipitation.
- Some precipitation falls as snow that accumulates as glaciers and ice caps that can store frozen water for several years.
- The rest falls as rain into the oceans or on the land. The water from the land flows into the rivers, ponds and lakes that eventually falls into the oceans.
This is how the water is returned back to the oceans.
