What is the layer of the atmosphere with coldest temperatures -100 degrees Celsius?

The layer of the atmosphere with the coldest temperatures, reaching around -100 degrees Celsius, is the mesosphere. This layer extends from approximately 50 to 85 kilometers (31 to 53 miles) above the Earth's surface. Temperatures decrease with altitude in the mesosphere, making it the coldest atmospheric layer. It is situated above the stratosphere and below the thermosphere.