The Troposphere

weather · atmosphere · air layers · climate

Closest layer to us. The troposphere is the lowest layer of Earth's atmosphere, sitting right above the ground where we live. On average, it extends about 13 kilometers (8 miles) straight up into the sky, though it's thicker over the tropics and thinner over the polar regions.

Where weather lives. This is the only layer where most weather actually happens, including rain, snow, lightning, and wind. It contains 99% of all the water vapor and aerosols in the entire atmosphere, which is why clouds form here.

Commercial planes fly here. When you board a commercial airplane, it cruises through the troposphere at heights between 10 and 12 kilometers up. This is the layer where the air is dense enough for planes to fly efficiently.

Most of our air. Even though the troposphere is just one layer, it holds 80% of the entire mass of Earth's atmosphere. All the other layers above it combined have much less air than this single lowest layer.