Processes Of The Water Cycle Flashcards
Define precipitation
Water or ice that falls from clouds towards the ground
Causes of precipitation?
When atmospheric vapour cools to its dew point and condenses into tiny water/ ice particles to form clouds.
Eventually the particles aggregate, reach a critical size and fall as precipitation.
How latitude impacts precipitation
In high latitudes, it is more likely to fall as snow and may remain on ground for many months so there is a lag time between snowfall and run off.
Why does high intensity precipitation move rapidly overland into streams/rivers?
It is falling at a rate which exceeds infiltration capacity of the soil
Define transpiration?
The diffusion of water vapour from the stomata of plants
What % of atmospheric moisture is the result of transpiration?
10%
Factors that influence transpiration give example for one
Temperature, wind speed and water avaliability to plants e.g. deciduous trees shed their leaves in climates with cold/dry climates to reduce moisture lost through transpiration
Define condensation
The phase change of vapour to liquid water when air is cooled to its dew point.
At dew point, air becomes saturated with vapour causing condensation
What process causes clouds to form? How does this process influence cumuliform clouds
Condensation.
Cumuliform clouds most often form when air is hested locally through contact to the Earth’s surface. Causes air parcels to rise freely through the atmosphere, expand and cool. As cooling reaches the dew point, condensation happens and clouds begin to form.
What does condensation at/ near ground produce? What influence does this product have?
Produces dew and fog.
They deposit large amounts of moisture on vegetation and other surfaces
Catchment hydrology: evaporation
The main pathway by which water enters the atmosphere.
Heat is needed to break molecular bonds of water but this does not cause the water to get hotter.
Energy is absorbed as latent heat and released later in condensation.
Catchment hydrology: interception and factors impacting interception loss
Rainwater that is breifly intercepted is through fall.
Intercepted water that flows to the ground along the branches and stems is known as stemflow.
Factors affecting interception loss: interception storage capacity, wind speed, vegetation type etc.
Catchment hydrology: what are the two ways that rain entering the ground gets to streams/ rivers without entering storage?
Infiltration and overland flow
Catchment hydrology: groundwater levels in chalk in S.England throughout the yr
Late Oct- late Jan: water table starts to rise as temp and evapotranspiration falls. This is known as recharge
Spring-early autumn: reaching the lowest point in early autumn due to higher temp and evapotranspiration
Catchment hydrology: cryospheric processes
Ablation is the loss of ice from snow, glaciers etc. due to melting evaporation and sublimation
Rapid thawing of snow in Pennines in winter is a common cause of flooding in the Vale of York
