õhukeskkonna

õhukeskkonna refers to the thin environment or atmosphere, commonly used in Estonian contexts to describe the very outer layers of a planet's atmosphere. This region is characterized by extremely low air density and pressure, where the concept of a continuous fluid becomes less applicable. Interactions between particles are more significant than the collective behavior of the atmosphere.

In the context of Earth, the õhukeskkond can encompass the exosphere and parts of the thermosphere. These regions are where the atmosphere gradually fades into outer space. Satellites and spacecraft often operate within or traverse these extremely thin atmospheric layers. While the density is minimal, there can still be enough atmospheric drag to affect the orbits of low-Earth orbit satellites over time, requiring periodic boosts to maintain altitude.

The composition of the õhukeskkond differs from denser atmospheric layers, with lighter gases like hydrogen and helium becoming more prevalent at higher altitudes. Understanding the properties of this thin environment is crucial for space exploration, satellite operations, and atmospheric modeling of planetary bodies. It represents the boundary where the familiar atmosphere of a planet meets the vacuum of space.