The water cycle Flashcards
When does permafrost form?
When temperatures are so low in the air that the soil and groundwater freezes.
When did glacial periods start
2.58 million years ago
What is ablimation
occurs when outputs exceed inputs and glaciers melt
what is accumilation
where inputs of snow and ice exceed the outputs and ice caps increase
how many glacial periods have there been
5 meaning we are in quarternary glaciation
what are interglacial periods
when ablimation exceeds accumilation and the hydrological cycle as we know it returns
what happened in the last glacial period
- sea levels were approximately 120m lower than present
- glaciers covered large parts of Europe, North America, and Siberia
- represents interruptions in the hydrological cycle
what do we label the processes permafrost and glacial periodss
cryospheric periods
What’s are examples of inputs into the water cycle
infiltration- when water soaks through the soil
precipitation- when water is deposited onto ground (hail,snow, rain, fog)
percolation- water moving from surface layers of the soil into deeper layers of soil and rock
what is percolation
water moving from surface layers of the soil into deeper layers of soil and rock
what is an example of a store in the water cycle
groundwater store- water held below the water table in aquifers
what can be an output if the water exits the drainage basin
condensation- the process by which water vapour turns to water
what factors influence the evapouration rate of water
- the amount of solar energy
- availability of water
- humidity of the air (the more saturated the air is, the slower the rate of evapouration)
- temperature (warmer air holds more water)
What happens to air temperature when evaporation occurs
evaporation uses energy in the form of latent heat and so cools the air when it occurs
what is condensation and when does it occur
- excess water in the air is converted to liquid
- occurs when air cools and therefore is less able to hold water vapour
- if air is cooled sufficiently, it will get to a temperature at which it is saturated (dew temp)
what does water need to condense on
condensation nuclei or surfaces that are below dew point temperature
what happens if the condensation surface is below zero
the water sublimates changing from gas to solid in the form of frostl
what is overland or surface flow
tarmac surfaces or hard baked soil causes water to run along the surface
what is throughflow
water moving down hill through soil layers, the soil concentrates along roots and soil weaknesses
what is groundwater flow
water moving along rocks below the ground
what is intercetion
- plants trap precipitation
- some water flows down the stem as stem flow
- precipitation may evaporate directly off the leaf, never reaching the ground
what is evaporation
water changing from liquid to gas (water vapour) and it returning to the atmosphere
what is channel flow
water moving downhill within rivers- temporary store
what is evapotranspiration
combination of evaporation and transpiration (water leaving the leaf through the stomata)
- both are often grouped together so its easily calculated