Mount Everest's summit is deadly cold because the thin atmosphere cannot trap heat.

The summit of Mount Everest sits at 8,848.86 meters above sea level, placing it in the upper reaches of the troposphere where the air is exceptionally thin. According to the National Geographic Society, the air pressure at the peak is approximately 337 mbar, compared to 1,013 mbar at sea level. This low pressure means there are fewer gas molecules to absorb and radiate long-wave thermal energy back to the surface.Temperature on the mountain follows the environmental lapse rate, which averages a drop of about 6.5°C for every 1,000 meters of elevation gain. During the winter months, the summit often intersects with the subtropical jet stream. This high-altitude wind current can reach speeds over 280 km/h, creating a wind chill effect that makes the perceived temperature significantly lower than the actual air temperature.Human physiology is also a major factor in the danger. In the 'Death Zone' above 8,000 meters, oxygen levels are so low that the body cannot maintain basic metabolic functions. Without sufficient oxygen, the mitochondria in cells cannot produce enough ATP to fuel thermogenesis. This leads to rapid hypothermia as the body prioritizes core organs over extremities, often resulting in severe frostbite within seconds of exposure.