Which is the warmest layer of the atmosphere?

The thermosphere is a layer of Earth's atmosphere. The thermosphere is directly above the mesosphere and below the exosphere. It extends from about 90 km (56 miles) to between 500 and 1,000 km (311 to 621 miles) above our planet. Based on the vertical temperature profile in the atmosphere, the thermosphere is the highest layer, located above the mesosphere.