Processes driving change in the magnitude of stores- Water Cycle Flashcards
What are the 4 processes that change the size of stores in the water cycle?
-Evaporation
-Condensation
-Precipitation (convectional, relief, frontal)
-Cryospheric processes at hillslope/drainage basin
Why does evaporation occur?
-Sun gives water energy, so bonds between molecules can be broken , latent heat is also needed for this process as bonds are so strong.
-When evapo occurs it cools the surroundings
What 3 factors affect the rate of evaporation?
relative humidity
saturation
dew point temperature
What is relative humidity?
The amount of water vapour in the air at a given temp, compared to how much the air can possibly hold at that temp
What is saturation?
If something is saturated it means 100% relative humidity- as much as the atmosphere can hold at a given time
What is dew point temperature?
If air = saturated
Air cannot hold anymore water vapour or not cold enough , it will condense
Affected by humidity
More moisture + higher dew point
What is condensation?
Water vapour absorbs heat and as water vapour condense it cools temp
Warmer air = more vapour = warmer global temps
Cooler air = less vapour = Poles (North and South) are dry due to less condensation
What scale does evaporation cool surroundings?
Local scale
What scale does condensation cool temperature?
Larger scale than evapo
What factors affect the rate of condensation?
-occurs bc water vapour loses energy, atmosphere becomes saturated and reaches dew point temp
-occurs if temp suddenly drops- air becomes saturated= new dew point temp
What are condensation nuclei?
Particles or surfaces (e.g leaves or windows) that are below dew point temp so condensation turns into clouds (particles in atmosphere)
What are 3 examples of condensation nuclei?
Dust, salts and aerosols
What is precipitation?
Occurs when there are too many water droplets in the air to defy gravity
Give 4 examples of precipitation
-Rain
-Hail
-Sleet
-Snow
What are the 3 forms of precipitation?
-Convectional
-Frontal
-Relief
What is convectional rainfall?
-Driven by energy from sun
-More heat = more evapo/conden
-More clouds/more rain
Give an example of where convectional rainfall occurs
The rainforest (equator)
What is relief rainfall?
-prevailing wind towards windward side
-low pressure (hot air rises/forced upwards)
-high pressure (cooler air sinks = condensation, dry descending air)
What is frontal rainfall?
-warm air holds more moisture, less dense
-warm air rises
-cold front = more dense
-cold air sinks
-every loom loss -1 degrees
Name the 2 cryospheric processes
Accumulation and Ablation
Define accumulation
The build up of snow and ice, will make glacier grow in size
Define ablation
The melting of ice, reduces glacier size, happens at snout of glacier
Define glacier mass balance
The balance between accumulation and ablation
Define positive mass balance
-Accumulation is greater than ablation
-Accumulation> Ablation
