thermosfeer

Thermosfeer, also known as the thermosphere, is the outermost layer of Earth's atmosphere. It lies above the mesopause, roughly at altitudes of 85–90 kilometers, and extends upward to about 500–1000 kilometers, though the upper boundary (the thermopause) shifts with solar activity. In this layer, temperature increases with height due to the absorption of extreme ultraviolet and X-ray radiation by atmospheric gases, especially atomic oxygen. Despite high temperatures, the air is extremely tenuous, so energy transfer by convection is negligible and a human would feel very cold.

The thermosphere contains very low air density and a composition dominated by light gases. At lower thermosphere altitudes, molecular nitrogen and atomic oxygen are common; as height increases, helium and hydrogen become more prevalent. The region overlaps with the ionosphere, where solar radiation ionizes particles, creating free electrons that influence radio propagation and satellite communication.

Phenomena associated with the thermosphere include auroral activity, driven by interactions between charged particles and Earth's magnetic field, particularly near polar regions. The layer is also highly affected by solar activity; during solar storms, heating and expansion can increase satellite drag and alter orbital paths. The International Space Station and many satellites operate within or pass through the thermosphere.

Significance lies in its role in atmospheric chemistry, space weather effects, and the propagation of radio waves through the ionized upper atmosphere. Its properties vary with the solar cycle and geomagnetic conditions, making it a dynamic region rather than a sharply defined shell.