Atmospheric layers and global circulation

Earth's atmosphere is layered by how temperature changes with height. In the troposphere, the lowest layer, reaching about 8 to 16 kilometers up, air is warmed mainly from the ground, so temperature drops with altitude, and nearly all weather happens there; it holds about three quarters of the atmosphere's mass. In the stratosphere above it, up to about 50 kilometers, temperature rises with height because the ozone layer absorbs harmful ultraviolet radiation from the Sun. The mesosphere, where most meteors burn up, gets colder again, and in the thermosphere the very thin air absorbs high-energy solar radiation and reaches very high temperatures, and auroras glow. Air pressure and density drop steadily with altitude. Unequal heating, with more solar energy reaching the tropics than the poles, drives a global circulation that carries heat toward the poles. Warm, moist air rises near the equator and sinks around 30 degrees latitude, forming Hadley cells that create the rainy tropics, the dry subtropical deserts, and the trade winds; Ferrel cells in the midlatitudes and polar cells near the poles complete the pattern. Earth's rotation deflects moving air, the Coriolis effect, to the right in the Northern Hemisphere and to the left in the Southern, turning these flows into the easterly trade winds and the midlatitude westerlies. Jet streams, fast, narrow winds near the top of the troposphere, form where warm and cold air meet and steer storms.

This explanation is AI-generated and can occasionally be wrong. 🚩 Report