PRECIPITATION
IS release of water from atmosphere to reach surface of earth e.g. rainfall, snow, hail, sleet
REQUIRES

cooling of atmosphere usually by uplift of air through atmosphere (caused by heating from earth's surface, an air mass being forced to rise over an obstruction - mountain - or low pressure weather system where air is constantly being forced upwards.,
nuclei for water vapour to condense on e.g. small dust particles, sea salts, smoke particles
growth of the water/ice droplets (condensation-formed, collision-formed or Bergeron-process-formed)

Dewfall is another form of precipitation but is not normally a major part of hydrological cycle

AMOUNT OF PRECIPITATION influenced by Static and Dynamic influences
Static influences (of decreasing impact)

Altitude - due to effect on temperature
Aspect - those facing away from predominant weather patterns will receive less rainfall than those facing them.
Slope - normally ignored

RAIN SHADOW EFFECT (static) where a large and high land mass blocks the rain, causing it to fall on one side while preventing it from moving to the other (e.g. southern alps)
Dynamic (changing) mainly caused by weather variations

Forest Rainfall Partitioning - once rain reaches tree canopy various things can happen

Throughfall - rain falls to ground directly or indirectly via leaves branches. Amount that reaches ground determined by canopy (cover one measure of which is Leaf Area Index - surface area of all leaves in canopy to surface area of ground), canopy storage capacity and rainfall characteristics (intensity, angle etc.)
Stemfall
Interception loss
Interception gain

	Created by CATRIONA McKay about 9 years ago

Note on Precipitation, created by CATRIONA McKay on 19/09/2015.

Precipitation