Highaltitude
High altitude refers to elevations where the atmosphere is noticeably thinner than at sea level. There is no single universal boundary; the term is used differently in aviation, medicine, and mountaineering. In general, high altitude begins around 2,000–3,000 meters (about 6,500–9,800 feet) above sea level, where air density and oxygen partial pressure decline markedly. In aviation, high-altitude flight commonly denotes operations at flight levels of about 18,000 feet (roughly 5,500 meters) and above, with pressurized cabins and supplemental oxygen for occupants.
Atmospheric conditions at high altitude include lower air pressure, reduced humidity, and cooler temperatures. The transition
Humans experience hypoxia as altitude increases, leading to altitude sickness and, at higher elevations, risk of
Applications of high-altitude study include aviation design, mountaineering safety, physiology and medicine, atmospheric science, and ecology