Geography Reference
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and is influenced by whether a station is on a sunny or a shaded slope, the disposition
of winds and clouds, and the nature of the slope surface. Snowcover and snowmelt each
act to lower atmospheric temperatures (Takechi et al. 2002). A convex slope has qual-
ities of heat retention different from those of a concave slope. A high valley will heat
up more during the day (and cool down more at night) than an exposed ridge at the
same elevation. Nevertheless, broad averages smooth out the extremes and individual
differences, generally showing a steady and progressive decrease in temperature with
increased elevation (Minder et al. 2010).
MOUNTAIN MASS ( MASSENERHEBUNG ) EFFECT
Large mountain systems create their own surrounding climate. The greater the surface
area or landmass at any given elevation, the greater the effect on its own environment.
Mountains serve as elevated heat islands where solar radiation is absorbed and trans-
formed into long-wave heat energy, resulting in much higher temperatures than those
found at similar altitudes in the free air (Chen et al. 1985). Accordingly, the larger the
mountain mass, the more its climate will vary from the free atmosphere at any given
altitude. This is particularly evident on high plateaus where treeline and snowline often
occur at higher elevations than on isolated peaks at the same elevation. On the broad
general level of the Himalaya, at 4,000 m (13,100 ft) it seldom freezes during summer,
while on the isolated peaks at 5,000 m (16,400 ft) it seldom thaws (Peattie 1936).
TABLE 3.3
Temperature Conditions with Elevation in the Eastern Alps
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