Alailmakehälle

Alailmakehälle is a Finnish term formed from ala- meaning lower, ilmakehä meaning atmosphere, and the allative suffix -lle, which marks direction toward or into something. In scientific Finnish, alailmakehälle refers to the lower portion of the Earth’s atmosphere, i.e., the atmospheric layer that is in direct contact with the surface.

Scope and usage

In meteorology, atmospheric chemistry and climate science, alailmakehälle denotes processes, phenomena or measurements situated in the lower atmosphere. The region typically encompasses the troposphere and, depending on context, the lower part of the stratosphere. Its vertical extent varies with latitude, season, and atmospheric conditions, ranging roughly from the surface up to about 8–15 kilometers. The term is used in Finnish texts to specify where activity occurs or where effects are observed, for example in relation to emissions, weather formation, or air quality.

Importance

The lower atmosphere is central to weather systems, radiative transfer, gas exchanges with the surface, and the cycling of aerosols and trace gases. It hosts the planetary boundary layer, where ground-level processes strongly influence atmospheric composition and dynamics. Because human activities predominantly interact with the lower atmosphere, alailmakehälle is a common focal point in studies of pollution, climate forcing, and environmental policy.

Relation to other terms

Alailmakehälle is contrasted with yläilmakehä (the upper atmosphere). Related Finnish terms include ilmakehä (atmosphere) and specific layers like tropopuause and the planetary boundary layer, which provide more detailed vertical structure within the lower atmosphere.

See also

Ilmakehä, tropo-/stratosfääri, yläilmakehä, planetary boundary layer.