Mountain Climate - Mountain Geography: Physical and Human Dimensions - page 96

continental station (A) experiences a small daily temperature range (read vertically) but a large
annual range (read horizontally). Conversely, the high-altitude tropical station (B) experiences a
much greater daily temperature range than the annual range. (Adapted from Troll 1958: 11.)
The decrease in water vapor with altitude may seem somewhat difficult to explain,
since precipitation increases with elevation. The two phenomena are not directly re-
lated, however. Precipitation results from the lifting of moist air from lower elevations
upward into an area of lower temperature. Increasing precipitation does create a more
humid environment in mountains, at least for part of the year and up to certain elev-
ations, but eventually signs of aridity increase. Aridity at high elevations is related, in
part, to lower barometric pressure, stronger winds, porous well-drained soils, and the
intense sunlight.
The greater aridity of high-elevation environments is evident from the plants and
animals, many of which have adapted to a dry environment. Thick, corky bark and
waxy leaves are common in alpine plants (Körner 2003). Mountain sheep and goats
and their cousins, the llama, guanaco, alpaca, chamois, and ibex, can all live for pro-
longed periods on little moisture. Geomorphologically, eolian processes become increas-
ingly important in higher landscapes, and the low availability of moisture is reflected in
soil development (Bach 1995). One physiological stress reported by climbers on Mount
Everest is a dryness of the throat and a general desiccation. Air-dried meat is a provin-
cial dish in the high Engadine of Switzerland, and pemmican and jerky were both im-
portant in the mountains of western North America. In the Andes, an ancient method ex-
ists for producing dried potatoes ( chuño ) in the high, dry air above 3,000 m (10,000 ft).
Permanent settlement at higher elevations apparently depended upon the development
of this technique of food preservation (Troll 1968). Most mummification of the dead in
Peru, Bolivia, and Chile occurred naturally, resulting from the aridity of the coastal foot-
hill regions. Although rare, the Incas performed human sacrifices and buried bodies on
mountain summits where the freezing conditions allowed mummies to be exceptionally
well preserved (Reinhard 2005).