Physiology of Finfish and Shellfish (2+1)

1.2.2.The Hydrological Cycle or water cycle

It is the journey water takes as it circulates from the land to the sky and back again.

Illustration of Hydrological cycle or water cycle

This cycle is made up of a few main parts:

1. Evaporation: Evaporation is when the sun heats up water in rivers or lakes or the ocean and turns it into vapor or steam. The water vapor or steam leaves the river, lake or ocean and goes into the air.
2. Transpiration: Transpiration is the process by which plants lose water out of their leaves. Transpiration gives evaporation a bit of a hand in getting the water vapor back up into the air.
3. Condensation: Water vapor in the air gets cold and changes back into liquid, forming clouds. This is called condensation.
4. Precipitation: Precipitation occurs when so much water has condensed that the air cannot hold it anymore. The clouds get heavy and water falls back to the earth in the form of rain, hail, sleet or snow
5. Collection: When water falls back to earth as precipitation, it may fall back in the oceans, lakes or rivers or it may end up on land. When it ends up on land, it will either soak into the earth or become part of the “ground water” that plants and animals use to drink or it may run over the soil and collect in the oceans, lakes or rivers where the cycle starts.