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Trees cannot grow at high altitude, because of cold temperature or lack of available moisture. [82]: 51 The lack of trees causes an ecotone, or boundary, that is obvious to observers. This boundary is known as the tree line. The highest-altitude plant species is a moss that grows at 6,480 m (21,260 ft) on Mount Everest. [83]
The layers are to scale. From the Earth's surface to the top of the stratosphere (50km) is just under 1% of Earth's radius. The exosphere is a thin, atmosphere-like volume surrounding a planet or natural satellite where molecules are gravitationally bound to that body, but where the density is so low that the molecules are essentially collision ...
The troposphere is the lowest layer of Earth's atmosphere. It extends from Earth's surface to an average height of about 12 km (7.5 mi; 39,000 ft), although this altitude varies from about 9 km (5.6 mi; 30,000 ft) at the geographic poles to 17 km (11 mi; 56,000 ft) at the Equator, [23] with some variation due
Regions on the Earth's surface (or in its atmosphere) that are high above mean sea level are referred to as high altitude. High altitude is sometimes defined to begin at 2,400 meters (8,000 ft) above sea level. [8] [9] [10] At high altitude, atmospheric pressure is lower than that at sea level. This is due to two competing physical effects ...
Heating of solids, sunlight and shade in different altitudinal zones (Northern hemisphere) [5] A variety of environmental factors determines the boundaries of altitudinal zones found on mountains, ranging from direct effects of temperature and precipitation to indirect characteristics of the mountain itself, as well as biological interactions of the species.
The effects of high altitude on humans are mostly the consequences of reduced partial pressure of oxygen in the atmosphere. The medical problems that are direct consequence of high altitude are caused by the low inspired partial pressure of oxygen, which is caused by the reduced atmospheric pressure, and the constant gas fraction of oxygen in ...
Depending on geographical and environmental pressures, high-altitude adaptation involves different genetic patterns, some of which have evolved not long ago. For example, Tibetan adaptations became prevalent in the past 3,000 years, an example of rapid recent human evolution. At the turn of the 21st century, it was reported that the genetic ...
The mesosphere, which on Earth lies between the altitudes of about 50 and 80 kilometres (31 and 50 mi), sometimes considered part of the "middle atmosphere" rather than the upper atmosphere; The thermosphere, which on Earth lies between the altitudes of about 80 and 700 kilometres (50 and 435 mi) The exosphere, which on Earth lies between the ...