Why Does Heat Rise?

By Staff WriterLast Updated Mar 31, 2020 7:40:09 PM ET
skyseeker/CC-BY 2.0

Hot air rises because when a substance is hot, its molecules are farther apart, which makes the hot air less dense and, therefore, lighter than cooler air. Air is generally warmer nearer the surface of the Earth because of the sun's radiating heat. When hot air rises, it starts to get cooler and eventually it sinks back down to the surface.