The thermosphere lies between the exosphere and the mesosphere. “Thermo” means heat, and the temperature in this layer can reach up to 4,500 degrees Fahrenheit. If you were to hang out in the thermosphere, though, you would be very cold because there aren't enough gas molecules to transfer the heat to you. Therefore, the temperature in the troposphere also decreases with height in response. As one climbs higher, the temperature drops from an average around 62°F (17°C) to -60°F (-51°C) at the tropopause. Temperatures in the upper thermosphere can range from about 500° C (932° F) to 2,000° C (3,632° F) or higher. The boundary between the thermosphere and the exosphere above it is called the thermopause. At the bottom of the thermosphere is the mesopause, the boundary between the thermosphere and the mesosphere below.Because there are relatively few molecules and atoms in the thermosphere, even absorbing small amounts of solar energy can significantly increase the air temperature, making the thermosphere the hottest layer in the atmosphere.

The Earth's temperature range in Fahrenheit is from 2,700 degrees Fahrenheit (1,500 degrees Celsius) in the uppermost atmosphere to a global average temperature of around 59 degrees Fahrenheit (15 degrees Celsius) near the surface. The thermosphere is often considered the "hot layer" because it contains the warmest temperatures in the atmosphere. Temperature increases with height until the estimated top of the thermosphere at 500 km. Temperatures can reach as high as 2000 K or 1727 ºC in this layer. While still extremely thin, the gases of the thermosphere become increasingly denser as one descends toward the earth. As such, incoming high energy ultraviolet and x-ray radiation from the sun begins to be absorbed by the molecules in this layer and causes a large temperature increase. The temperature of the thermosphere increases with height due to absorption of solar radiation within the ionosphere, which is concentrated in the upper thermosphere. There is very little to absorb solar radiation in the mesosphere, and it receives very little heat from below, hence the thermosphere is much warmer. The Earth's layers from coolest to hottest are: crust, mantle, outer core, and inner core. The crust's temperature can vary from the air temperature on top of the crust to 1600 degree Fahrenheit. Thermosphere is the hottest layer of the atmosphere while Mesosphere is the coldest layer of the atmosphere. Solar activity strongly influences temperature in the thermosphere; the temperature of this layer can rise as high as 1500 °C. X-ray and UV radiation from the Sun is absorbed in the thermosphere. Located between about 80 and 700 kilometers (50 and 440 miles) above Earth's surface is the thermosphere, whose lowest part contains the ionosphere. In this layer, temperatures increase with altitude due to the very low density of molecules found here. It is both cloud- and water vapor-free.