The coldest layer of Earth's atmosphere is the mesosphere. Temperatures in this layer can drop as low as -90°C (-130°F) near the top. This layer sits above the stratosphere and below the thermosphere, extending from about 50 to 85 km (31 to 53 miles) above the planet. The mesosphere is difficult to study, and less is known about it compared to other layers of the atmosphere.
Why is the mesosphere so cold?
The mesosphere is primarily heated from below. As you go higher in the atmosphere, there are fewer air molecules to absorb the sun's energy. Additionally, the mesosphere is where most meteors burn up, adding to its heat loss. These factors contribute to the mesosphere's extremely low temperatures.
