The third layer of the Earth's atmosphere is called the mesosphere. It extends from the top of the stratosphere, at about 50 km (31 mi) above sea level, to the bottom of the thermosphere, at about 85 km (53 mi). The temperature in the mesosphere decreases with altitude, reaching a minimum of about -90 °C (-130 °F) at the mesopause, which is the coldest part of the Earth's atmosphere. The mesosphere is very thin, and air pressure is very low. It is also very calm, with little wind or weather activity.