mesosfeer

The mesosfeer is the Dutch term for the atmospheric layer known in English as the mesosphere. It is the third major layer of Earth’s atmosphere, situated above the stratosphere and below the thermosphere. In Dutch usage it covers roughly 50 to 85 kilometers above the surface, with the upper boundary, the mesopause, located around 85 to 90 kilometers.

In this layer, the air is very thin and the temperature generally decreases with altitude. The mesosphere contains the coldest temperatures in Earth’s atmosphere, reaching about -90 degrees Celsius near the mesopause. The cold conditions help sustain certain high-altitude phenomena and atmospheric chemistry.

Key phenomena in the mesosfeer include the burning up of most meteors as they enter the atmosphere and travel through this region. Noctilucent clouds, the highest clouds on Earth, form in polar regions during summer at altitudes around 80 to 85 kilometers. The layer also hosts metal layers from meteoric ablation, such as sodium and iron, which can affect the local chemistry and optical properties.

The mesosfeer is challenging to study due to its very low air density. Measurements come from sounding rockets, satellites, lidar, and radar observations, complementing models of atmospheric dynamics. Gravity waves originating in lower layers propagate into the mesosfeer, influencing temperature and density structure.

See also: Mesosphere.