1. Extreme Environment
CHAPTER 7

2. Challenging ENVIRONMENTS
Extreme Environments
Hot, arid environments
Cold and high altitude environments
Common characteristic: inhospitable to human habitation.
Global Distribution of Cold and High Altitude
Mountain range: [longest: Los Andes] [highest: Himalaya]

3. Mountain Range’s distribution

4. Glacial areas: a slowly mass or river of ice formed by the accumulation and compaction of snow on mountains or near de poles.
Periglacial areas: areas adjacent to glacial areas, and experience repeated freezing and thawing.

5. Why are Cold and High Altitude Extreme Environments?
First, sun’s rays strike the earth surface at a lower angle near the poles. So solar energy spreads on a larger area [less energy in polar areas than in equatorial areas]
Second, sun’s rays must penetrate a greater thickness of atmosphere near de polar [less heat reaches earth’s surface]
Third, a great proportion of heat that reaches the surface is reflected back due to albedo (reflectivity)

6. In mountain areas, the main factor causing differences in the landscape is altitude. The differences that are found globally from latitude 0 to 90 are mirrored by the differences we see rising from sea level to 9,000 meters elevation, In terms of geographical variation, the distance from the equator to the poles is the same as from sea level to the highest point in the world, even though the vertical distance is les than 10,000 meters.

7. There is a direct relationship altitude, air pressure and temperature
There is a direct relationship altitude, air pressure and temperature. The tendency for the atmosphere to become cooler with increasing altitude is the reason for permanently snow- covered caps in countries close to the Equator. To a large extent, the fall in temperature with increasing altitude mirrors the fall in temperature with increasing latitude.
As altitude increases , there are decreases in air density, water vapor, carbon dioxide, and impurities.
Fall in the air pressure with altitude = boiling point of water decreses
Higher altitude = higher intensity of ultra-violet radiation

8. Temperature, altitude and slope: slopes facing south receive more solar radiation and are expose to prevailing winds, rising air and soil temperature = differences in vegetation and land uses on the northern and southern slopes.
Windward side receives more precipitation than Leeward side of mountains.
Altitude and its effects on population? Question Bloc 7d

9. Extreme environment Links
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10. why are arid environments extreme?
Arid environment: potential evaporation exceeds potential precipitation
Desertification: process whereby desert expand into semi-arid areas or become more intense.
Desert
Traditionally: lack of rain, soil nutrient, vegetation and population
Now: most desert areas have abundance on vegetation and wildlife
It is important that aridity is NOT infertility

11. Global distribution of arid environment
Cold winter mid-latitude deserts
Cause: remoteness from source of atmospheric moisture
Rainshadow deserts
cause: orographic effect [precipitation dropped mainly in one side o the mountain, windward]
Desert of sub-tropical highs
Cause; equatorial zones receive more constant heating from the sun
West coast deserts
Cause: due to the subtropical high-pressure systems and cool ocean currents.