Atmosphere Layers

Temperature, pressure, and composition through the atmosphere

Earth's atmosphere is divided into layers based on temperature changes with altitude. The troposphere (0-12 km) contains 75% of atmospheric mass and all weather; temperature decreases at ~6.5°C/km. The stratosphere (12-50 km) contains the ozone layer (peak at ~25 km) that absorbs UV, warming the air — temperature increases with altitude. The mesosphere (50-85 km) is the coldest layer, where temperature drops again. The thermosphere (85-600 km) absorbs extreme UV and X-rays, reaching >1000°C, but feels cold due to low particle density. Pressure drops exponentially: halving roughly every 5.5 km. At 100 km (Kármán line), space officially begins.