Highelevation

High elevation refers to parts of the Earth's surface situated well above sea level, where the atmosphere is thinner and weather patterns differ from those at lower altitudes. There is no single fixed threshold, but elevations above about 1,500 meters (4,900 feet) are commonly described as high, with elevations over 2,500–3,000 meters (8,200–9,800 feet) often termed very high. Elevation is measured relative to mean sea level and is influenced by regional topography and geoid variations; in aviation, altitude is typically reported above mean sea level or above ground level.

Climate and environment at high elevation are characterized by cooler temperatures, greater diurnal temperature variation, and increased exposure to solar radiation due to thinner air. Air pressure and oxygen availability decline with altitude, affecting both weather and biological processes. Vegetation zones shift with altitude, producing distinct ecological belts such as montane forests, subalpine zones, and alpine tundra. Biodiversity often includes species specially adapted to lower oxygen levels, greater UV exposure, and harsher winds.

Physiology and acclimatization: humans and other animals experience reduced oxygen availability at high elevations. Acclimatization involves physiological changes such as increased ventilation, higher heart rate, and, over longer periods, greater red blood cell production. The pace of ascent and prior acclimatization influence tolerance; rapid ascent can lead to altitude-related illnesses.

Health considerations include acute mountain sickness and, in more severe cases, high-altitude pulmonary edema or cerebral edema. Prevention emphasizes gradual ascent, rest days, hydration, avoidance of alcohol, and, where appropriate, medical guidance or prophylaxis.

Human activity at high elevations includes mountaineering, tourism, and agriculture in specialized ecosystems; many high-elevation regions also play crucial roles in water resources and climate research. Notable high-elevation regions include the Himalayas, Andes, Ethiopian Highlands, Tibetan Plateau, Rocky and Alpine ranges.