Weather Exam 2 Prep
importance of fresh water in cryosphere
contains 97% of our fresh water in glacial ice and mntn snow (75% fresh water in western US)
components of cryosphere
1)continental ice sheets, ice shelves, caps, river and lake ice, and alpine glaciers
2) sea ice
3)permafrost
Northern Hemisphere snow cover
1)varies from about 2 million km^2 to 4 million in summer to 45 million to 47 million in winter
2)fresh, low density snow has high albedo: 80-90%
3) snow cover helps to keep the air temp lower, but keeps ground beneath it warmer
components of permafrost
1)melting of it releases greenhouse gases
2)permafrost cover important to ecosystems
3)permanently frozen ground
4)ground must be at or below 0degreesC for 2 or more years
5)can have pockets of unfrozen ground-Talik
6)heated from ground below and cooled from surface
7)temps change slowly-response to decadal and longer time spans
8)active layer- upper portion that responds to seasonal variation in temps
9)temp measurements indicate that temp of permafrost in northern hemisphere is warming
10)permafrost in NA likely to decrease by 20-35% by middle of this century
11)if it has high ice content, as pockets of ice melts, get depressions and small hills called thermokarst
12)pingos-hills with ice in center, frozen ground is forced up by underground water
Western Siberian Permafrost
1) area the size of France and Germany combined (app 1 mill sq km) in western Siberia is melting
2)as it melts, shallow lakes formed on surface
3) problem is that there are peat bogs underneath western Siberian permafrost
4)warmed an ave of 3C in past 40 yrs
5)est that the western Siberian peat bog thats bein exposed due to melting of permafrost contains 70 BILLION tons of methane
peat bogs underneath western Siberia permafrost
1)formed around 11,000 yrs ago at end of last glacial maxima
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