During and following uplift, mountains are subjected to the agents of erosion (water, wind, ice and gravity) which gradually wear the uplifted area down. Erosion causes the surface of mountains to be younger than the rocks that form the mountains themselves.[20] Glacial processes produce characteristic landforms, such as pyramidal peaks, knife-edge arêtes, and bowl-shaped cirques that can contain lakes. Plateau mountains, such as the Catskills, are formed from the erosion of an uplifted plateau.
Climate
A mountain in Carbon County, Utah
Main article: Alpine climate
Climate on mountains become colder at high elevations, due to the way that the sun heats the surface of the Earth.[21] The sun warms the ground directly, while the greenhouse effect acts as a blanket, reflecting heat back towards the Earth that would otherwise be lost to space. The greenhouse effect thus keeps the air at low elevations warm. As elevation increases, there is less greenhouse effect, so the ambient temperature goes down.[22]
The rate at which the temperature drops with elevation, called the environmental lapse rate, is not constant (it can fluctuate throughout the day or seasonally and also regionally), but a typical lapse rate is 5.5°C per 1,000 m (3.57°F per 1,000 ft).[23][24] Therefore, moving up 100 meters on a mountain is roughly equivalent to moving 80 kilometers (45 miles or 0.75° of latitude) towards the nearest pole.[25] This relationship is only approximate, however, since local factors such as proximity to oceans (such as the Arctic Ocean) can drastically modify the climate.[26] As the altitude increases, the main form of precipitation becomes snow and the winds increase.[27]
The effect of the climate on the ecology at an elevation can be largely captured through a combination of amount of precipitation, and the biotemperature, as described by Leslie Holdridge in 1947.[28] Biotemperature is the mean temperature, where all temperatures below 0 °C (32 °F) are considered to be 0 °C. When the temperature is below 0 °C, plants are dormant, so the exact temperature is unimportant. The peaks of mountains with permanent snow can have a biotemperature below 1.5 °C (34.7 °F)
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Climate
A mountain in Carbon County, Utah
Main article: Alpine climate
Climate on mountains become colder at high elevations, due to the way that the sun heats the surface of the Earth.[21] The sun warms the ground directly, while the greenhouse effect acts as a blanket, reflecting heat back towards the Earth that would otherwise be lost to space. The greenhouse effect thus keeps the air at low elevations warm. As elevation increases, there is less greenhouse effect, so the ambient temperature goes down.[22]
The rate at which the temperature drops with elevation, called the environmental lapse rate, is not constant (it can fluctuate throughout the day or seasonally and also regionally), but a typical lapse rate is 5.5°C per 1,000 m (3.57°F per 1,000 ft).[23][24] Therefore, moving up 100 meters on a mountain is roughly equivalent to moving 80 kilometers (45 miles or 0.75° of latitude) towards the nearest pole.[25] This relationship is only approximate, however, since local factors such as proximity to oceans (such as the Arctic Ocean) can drastically modify the climate.[26] As the altitude increases, the main form of precipitation becomes snow and the winds increase.[27]
The effect of the climate on the ecology at an elevation can be largely captured through a combination of amount of precipitation, and the biotemperature, as described by Leslie Holdridge in 1947.[28] Biotemperature is the mean temperature, where all temperatures below 0 °C (32 °F) are considered to be 0 °C. When the temperature is below 0 °C, plants are dormant, so the exact temperature is unimportant. The peaks of mountains with permanent snow can have a biotemperature below 1.5 °C (34.7 °F)
