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Lecture 2

GEG3107 Lecture 2: Lecture 2
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8 Pages
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Department
Geography
Course Code
GEG3107
Professor
Antoni Lewkowicz

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September 19, 2016
Essay outline:
- Avoid colloquial and emotive language
Lecture 2A Polar climates of past and present
- Weather station, including temperature loggers used to measure snow depth
Elements of climate:
- Climate = long term average of weather (at least 30 years)
30 year normal (available through Environment Canada)
- Updated every 10 years
Was chosen as 30 years is a sufficiently large sample size
- This is likely no longer true (first 10 & last 10 are very different)
- Main climate factors include: Air temperature, precipitation, wind speed & direction,
cloudiness, insolation (amount of sun, strongly tied to latitude), atmospheric pressure
Other factors: humidity, evaporation, soil temperature & moisture
- Stevenson’s screens are used to measure air temperature
Influences on climate:
- Latitude (isolation)
Def of Arctic/Antarctic circle: There will be 1 day of complete darkness and 1 day
of 24h sunlight (on the solstices)
Angle of the sun changes with position
- Elevation
Generally gets colder the higher into the atmosphere you go
Average lapse rate = 6.5°C/1000m
- But varies, especially in Arctic regions (can get warmer as you rise)
- Distribution of land and sea, especially in polar regions
Maritime vs Continental climates
- Oceanic currents (warm vs. cold)
Ex. Permafrost in Labrador & southern Quebec due to the influence of the
Labrador current, or Gulf Stream in Europe
- Air circulation + High and low pressure centers
- Size and distribution of mountains
- Prevailing winds
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find more resources at oneclass.com
Influences on Climate in the Polar Regions:
- Receive ~60% of the amount of insolation received at the equator
High values in the summer, but none in the winter
Much of the radiation received is reflected
Ice is very reflective, liquid water is very absorbent
- Dry, dust-free atmosphere so long-wave (infra-red) radiation is easily lost
Long-wave radiation is emitted by the Earth
- Average elevation of Antarctica is 2500 m
In addition the sea ice coverage doubles in the winter, which blocks oceanic heat
transfer
- Polar regions have a net radiation deficit, but they receive energy transfers from
equatorial regions
If not for this energy transfer the polar regions would be much colder
Atmospheric pressure and circulation:
- A polar vortex exists at each end of the Earth
Vortex = A large, persistent area of low pressure
Winds run from the west around the edges of the low pressure area
- Westerlies run counter-clockwise in the north, the vortex is asymmetrical
leading to a heat transfer towards the pole
- Westerlies run clockwise in the Antarctic, and the vortex is (roughly)
symmetrical
- Air Temperature:
Antarctic: “Cold Pole” is off-centre due to asymmetrical elevation
- Coldest temp recorded: - 89°C
- Map of mean annual temp
Arctic: Non-circular temperature pattern
- Coldest recorded temperature: - 68°C (Siberia)
- Map of mean January temperatures (left) and July (right)
In the Antarctic temperatures vary spatially from the Polar Plateau (center of
continent) to the coastal areas to the sub-Antarctic islands
- Continental climates have a large temp range & low precip; Maritime climates
- Surface Winds:
Antarctica surface winds are katabatic air drainage (cold air drainage) that flow
from the center of the continent towards the coast (with a slight deflection at the
coast)
Inexpressible Island: Very windy (basically all the time)
In the Arctic the winds take a while to build up & you can generally see/tell that
they are coming, but in the Antarctic the winds build much quicker and are much
more localized
- Winds are due to circulation systems in Arctic, but the katabatic winds
(Antarctic) can be very localized
find more resources at oneclass.com
find more resources at oneclass.com
- Precipitation:
Both regions are relatively arid (cold deserts)
Antarctica: Ice accumulation varies form >1000 mm/yr (peninsula) to <50 mm/yr
Past Environmental change:
- The last column (on right [decadal scale]) is wrong/out of date, substantial changes can
occur in the space of decades
- Plate tectonics: Had a larger effect of Antarctica than on the Arctic
About 38 MYA Australia fully separated from Antarctica
- Lead to a biological and climatic separation of Antarctica
In the lass 100 million years there has been very little change in the Northern
polar regions (little/no biological isolation)
- 60 MYA @ bottom, present (Holocene) @ top
There is some debate about whether the East Antarctic ice sheet has been stable
since its formation (14 MYA)
- Temperature graphs: Fluctuating periods of glaciation in the Quaternary
- Minimum average temperature for trees is ~10°C (in July)
- Global temperature difference between glacial and interglacial periods is ~ 5°C
- Isotopic analysis is used to find historic temperatures (ice cores)
16O and 18O ratios
- During the last glaciation (18,000 years ago) there were large areas of the Arctic that
were ice free (but incredibly cold) due to the extremely dry conditions
However, mammoths were still present in this area (Siberia)
- Tracking presence of DNA in soil
- Changes in Antarctic glacial ice, doesn’t include sea ice
Lecture 2B Sea ice in the Polar Regions
Ocean Water Structure and Circulation:
- The marine environment at the poles is different from other oceans due to the ‘cap’ of
cold surface water (also has a lower salinity) and the presence of sea ice for (at least) part
of the year
- Cross-section of the Arctic Ocean
Most or the Arctic ocean is actually Atlantic water
Surface water is colder than the underlying water, but its lower salinity keeps it at
the surface (less dense)
- Surface Arctic Ocean circulation:
Two major patterns: the transpolar drift and the Beaufort gyre
- Mass balance: Almost ½ the water that leaves the Arctic Ocean is Atlantic water
find more resources at oneclass.com
find more resources at oneclass.com

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Description
September 19, 2016 Essay outline: - Avoid colloquial and emotive language Lecture 2A – Polar climates of past and present - Weather station, including temperature loggers used to measure snow depth Elements of climate: - Climate = long term average of weather (at least 30 years)  30 year normal (available through Environment Canada) - Updated every 10 years  Was chosen as 30 years is a sufficiently large sample size - This is likely no longer true (first 10 & last 10 are very different) - Main climate factors include: Air temperature, precipitation, wind speed & direction, cloudiness, insolation (amount of sun, strongly tied to latitude), atmospheric pressure  Other factors: humidity, evaporation, soil temperature & moisture - Stevenson’s screens are used to measure air temperature Influences on climate: - Latitude (isolation)  Def of Arctic/Antarctic circle: There will be 1 day of complete darkness and 1 day of 24h sunlight (on the solstices)  Angle of the sun changes with position - Elevation  Generally gets colder the higher into the atmosphere you go  Average lapse rate = 6.5°C/1000m - But varies, especially in Arctic regions (can get warmer as you rise) - Distribution of land and sea, especially in polar regions  Maritime vs Continental climates - Oceanic currents (warm vs. cold)  Ex. Permafrost in Labrador & southern Quebec due to the influence of the Labrador current, or Gulf Stream in Europe - Air circulation + High and low pressure centers - Size and distribution of mountains - Prevailing winds Influences on Climate in the Polar Regions: - Receive ~60% of the amount of insolation received at the equator  High values in the summer, but none in the winter  Much of the radiation received is reflected  Ice is very reflective, liquid water is very absorbent - Dry, dust-free atmosphere so long-wave (infra-red) radiation is easily lost  Long-wave radiation is emitted by the Earth - Average elevation of Antarctica is 2500 m  In addition the sea ice coverage doubles in the winter, which blocks oceanic heat transfer - Polar regions have a net radiation deficit, but they receive energy transfers from equatorial regions  If not for this energy transfer the polar regions would be much colder Atmospheric pressure and circulation: - A polar vortex exists at each end of the Earth  Vortex = A large, persistent area of low pressure  Winds run from the west around the edges of the low pressure area - Westerlies run counter-clockwise in the north, the vortex is asymmetrical leading to a heat transfer towards the pole - Westerlies run clockwise in the Antarctic, and the vortex is (roughly) symmetrical - Air Temperature:  Antarctic: “Cold Pole” is off-centre due to asymmetrical elevation - Coldest temp recorded: - 89°C - Map of mean annual temp  Arctic: Non-circular temperature pattern - Coldest recorded temperature: - 68°C (Siberia) - Map of mean January temperatures (left) and July (right)  In the Antarctic temperatures vary spatially from the Polar Plateau (center of continent) to the coastal areas to the sub-Antarctic islands - Continental climates have a large temp range & low precip; Maritime climates - Surface Winds:  Antarctica surface winds are katabatic air drainage (cold air drainage) that flow from the center of the continent towards the coast (with a slight deflection at the coast)  Inexpressible Island: Very windy (basically all the time)  In the Arctic the winds take a while to build up & you can generally see/tell that they are coming, but in the Antarctic the winds build much quicker and are much more localized - Winds are due to circulation systems in Arctic, but the katabatic winds (Antarctic) can be very localized - Precipitation:  Both regions are relatively arid (cold deserts)  Antarctica: Ice accumulation varies form >1000 mm/yr (peninsula) to <50 mm/yr Past Environmental change: - The last column (on right [decadal scale]) is wrong/out of date, substantial changes can occur in the space of decades - Plate tectonics: Had a larger effect of Antarctica than on the Arctic  About 38 MYA Australia fully separated from Antarctica - Lead to a biological and climatic separation of Antarctica  In the lass 100 million years there has been very little change in the Northern polar regions (little/no bio
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