Alaskan Tundra: Key Knowledge Flashcards
Outline the location of the Alaskan tundra, from southern to northern limits.
From the Northern edge of coniferous forest to the Arctic Ocean.
What is the significance of the 10 degree July isotherm?
Climatic limit of tree line.
Mean temperatures are below..?
-15 degrees.
For how many months does the tundra have negative heat balance, with average monthly temperatures below freezing?
8-9 months.
Which part of the ground is not permanently frozen during the Arctic Summer?
Active Layer.
True or false: There are times in winter when there is no sunlight at all in 24 hours.
True.
Temperatures can plunge below..?
-30 degrees.
True or false: Daylight hours are also short in summer?
False.
Annual precipitation is less than…?
100mm in most areas.
What is the most common form of precipitation?
Snow.
Absolute humidity is high or low due to low temperatures?
Low.
What is the length of the growing season due to limited daylight hours and low temperatures?
3 months.
What is the sun’s energy used up for, leading to low temperatures at ground level?
Melting snow using latent heat.
True or false: There is a significant convention in summer when the ground warms up and the active layer of permafrost melts?
False: Ground temperatures still remain low so low convection.
Why is there limited groundwater and soil moisture stores? What flows are inhibited?
- Permafrost is a barrier.
- Infiltration, percolation, soil moisture recharge, groundwater flow.
Why is there a sharp increase in river discharge in spring?
- Thawing of active layer.
- Melting of accumulated snow and ice layer.
What is the minimum and maximum discharge of Yukon River?
- Minimum: 340 cumecs.
- Maximum: 24,600 cumecs.
Two reasons why permeability is low in the Alaskan tundra?
- Extensive permafrost.
- Impermeable precambrian metamorphic and igneous rock.
How many lakes are there in Alaska?
3 million lakes.
Where are the wetlands in the Alaskan tundra?
- Yukon river valley.
- Deltas.
- Coast esp off Bering Sea.
Explain why there are extensive wetlands, ponds, and lakes on the tundra during summer?
- Permafrost impedes drainage increasing surface water storage.
- Ancient rocks underlie the tundra. These have been eroded and weathered over millions of years, forming gentle, undulating plains.
- Flat relief reduces the speed of the overland flow through/ through flow in the active layer.
- Chaotic glacial deposits impede drainage, leading to waterlogging in Summer.
