Water cycle.

The water cycle (or hydrological cycle) is the cycle that water goes through on Earth.  Then, the water falls from the sky as rain, snow, sleet or hail. This is called precipitation. The water sinks into the surface and also collects into lakes, oceans, or aquifers. It evaporates again and continues the cycle.

Water cycle is defined as the way that water moves between being water vapor to liquid water and then back to water vapor. An example of water cycle is when water evaporates from oceans and then returns to the land in the form of rain. 

There are four main parts to the water cycle: Evaporation, Convection, Precipitation and Collection. 

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. We have already learnt about transpiration, did you know that transpiration gives evaporation a bit of a hand in getting the water vapor back up into the air!

 2) Convection

 Convection in the water cycle is when the air near the surface is heated, then rises taking heat with it. Water vapor in the air gets cold and changes back into liquid, forming clouds. This is called condensation. You can see the same sort of thing at home... Pour a glass of cold water on a hot day and watch what happens. Water forms on the outside of the glass. That water didn't somehow leak through the glass! It actually came from the air. Water vapor in the warm air, turns back into liquid when it touches the cold glass! 

3) 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. 

4) Collection/Storage

 A lot of the Earth's water does not take part in the water cycle very often. Much of it is stored. The Earth stores water in a number of places. The ocean is the largest storage of water. Around 96% of the Earth's water is stored in the ocean. We can't drink the salty ocean water, so fortunately for us, freshwater is also stored in lakes, glaciers, snow caps, rivers, and below the ground in groundwater storage.