Global Warming Today - The Water Cycle

The water cycle or the Hydrogen cycle is the continuous movement of water around the earth. It really is a cycle and have no true beginning or end, during the cycle water can be in solid, liquid of gaseous form. The water cycle is driven by the sun as it heats and then evaporates the water in our oceans which then turns to vapour and rises into the air. Ice and snow can sometimes turn from solid to gas without becoming water beforehand, evapotranspiration is a process where is water transpired from plants and then it is evaporated from the soil.

As air rises it takes water vapour with it up into the atmosphere where it is cooler, these cooler temperatures cause the vapour to condense and become clouds, these clouds are moved across the earth by air currents and when the collide they fall as rainfall (precipitation) Sometimes precipitation can fall as snow and can store water for thousands of years before they eventually thaw, then they do it is known as snowmelt.

The majority of rainfall goes straight back it to the seas and oceans the amount that falls on the ground is known as surface runoff, it can run off in to lakes and streams but much of it is soaked in to the ground where it falls, this is called infiltration some of this is stored deep in the ground for a great amount of time and some water stays close to the surface and goes back into oceans and other surface water as groundwater discharge.

There are many different process involving water and the hydrogen cycle:

Precipitation - This is mainly rainfall, but also snow, fog and sleet, around 505,000 km3 (121,000 cu mi) of water fall to the earth each year as precipitation

Canopy interception - This is precipitation that does not fall to the ground but is caught by plants and other foliage, this is finally evaporated back into the atmosphere.

Snowmelt - Caused by melting snow and ice

Runoff - The movement of water across land by surface runoff and channel runoff

Infiltration - Which is the movement of water from the ground surface to the ground which becomes soil moisture.

Subsurface Flow - This is the movement of water underground

Evaporation - This is the transformation of water as a liquid in to a gas, as it rises back into the atmosphere

Advection - As water is moved either in solid, liquid or gas through the atmosphere

Condensation - Waster is turned from vapour to liquid water which produces clouds and fog

Transpiration - Water is released from plants back in to the air in gaseous form