Alpine climate
For the climate of the mountains named the Alps, see Climate of the Alps.
Alpine climate is the average weather (climate) for a region above the tree-line. This climate is colder at high elevations, due to the lapse rate of air: air will tend to get colder as it rises, since it expands. The dry adiabatic lapse rate is 10°C per km of elevation or altitude. Therefore, moving up 100 meters on a mountain is roughly equivalent to moving 80 kilometers (45' (0.75°) of latitude) towards the pole . This relationship is only approximate, however, since local factors such as proximity to oceans can drastically modify the climate.
There have been several attempts at quantifying what constitutes an alpine climate.
Climatologist Wladimir Köppen demonstrated a relationship between the Arctic and Antarctic tree lines and the 10°C summer isotherm; i.e., places where the average temperature in the warmest calendar month of the year is below 10°C cannot support forests. See Köppen climate classification for more information.
However, Tierra del Fuego lies outside the polar region in Nordenskiöld's system, but part of the island (including Ushuaia, Argentina) is reckoned as being within the Antarctic under Köppen's.
In 1947, Holdridge improved on these schemes, by defining subpolar, of the low temperature is caused by latitude).
