Here's why:
* Temperature Decreases with Altitude: In general, temperature decreases as you go higher in the atmosphere. This is because the air gets thinner and there are fewer molecules to absorb and retain heat from the sun.
* Mesopause: The mesosphere is sandwiched between the stratosphere and the thermosphere. The boundary between the mesosphere and the thermosphere is called the mesopause, and it is the coldest point in the entire atmosphere, with temperatures reaching around -90°C (-130°F).
* Limited Heat Source: The mesosphere doesn't receive much direct sunlight, and it doesn't have the ozone layer (like the stratosphere) to absorb heat. This lack of heat sources contributes to its extremely low temperatures.
While the thermosphere has very high temperatures, these are due to the absorption of solar radiation by a few gas molecules, not the overall temperature of the layer.
