The coldest layer of the atmosphere is the mesosphere.
In the mesosphere, temperatures can drop as low as -90 degrees Celsius (-130 degrees Fahrenheit). This layer extends from about 50 to 85 kilometers (31 to 53 miles) above the Earth’s surface. As you move higher into the mesosphere, the air becomes thinner, and the temperatures continue to decrease. The mesosphere is also where most meteors burn up upon entering the Earth’s atmosphere, which adds to its intriguing nature.
The cooling in the mesosphere occurs because it is the layer where the majority of the ultraviolet radiation from the sun is absorbed by ozone, causing the temperature to drop as you ascend. This unique thermal profile distinguishes the mesosphere from the layers above and below it, making it the coldest layer in our atmosphere.