The water cycle is describing the full cycle of water interactions between the different geospheres: atmosphere, hydrosphere, pedosphere and cryosphere.
- Evapo-transpiration takes place wherever water in water bodies or ground and heat energy are available.
- The direct change from frozen water (ice or snow) to water vapour is called sublimation.
- Water vapour is transported by air over long distances and might either condensate over the oceans or over land.
- Precipitation takes place whenever the dew point (condensation point) has been reached; precipitation can be rain, mist, snow or hail; most portion of water vapour condensate on oceans and is leading to precipitation there.
- Precipitation over land is leading to surface run-off, infiltration and percolation; the processes are very much depending on landscape character, such as altitude, slope, curvature, temperatures, vegetation cover, soil type, agriculture, agro-forestry, etc.
- Rainfall might not directly tough the ground but vegetation: interception and evapo-transpiration lead again to increase of water vapour and condensation processes
- Water that touched the ground is either infiltrating into the soil and later percolating into the rock or is leading to surface run-off and is directly increasing lake levels or discharge of rivers; finally all water that will not evapo-transpirate is reaching the oceans (except water that is reaching areas deep down and leading to fossil ground water)
All interactions together are are always closing the loop among the four spheres. The hydrological cycle has not a defined starting or end point, since it is a dynamic process without a starting or end point.