Långvågsregim

Långvågsregim is a term used in atmospheric physics and meteorology to describe a specific condition where longwave radiation plays a dominant role in the energy balance of the atmosphere. This regime is particularly relevant during nighttime, especially under clear sky conditions, and can also be significant in polar regions during periods of low solar insolation.

In the långvågsregim, the cooling of the Earth's surface and the lower atmosphere through infrared radiation emission is more pronounced than the warming effects from incoming solar radiation or other energy transfer processes. This net outgoing longwave radiation flux leads to a decrease in temperature. The rate of cooling is influenced by factors such as atmospheric humidity, cloud cover (though typically clear skies are associated with a strong långvågsregim), and the presence of greenhouse gases.

The concept of långvågsregim is important for understanding diurnal temperature variations, frost formation, and the development of temperature inversions. In remote sensing, it helps in interpreting satellite-based temperature measurements where surface emissivity and atmospheric transmission of longwave radiation are key considerations. The term highlights the radiative component of atmospheric cooling, distinguishing it from advective or convective cooling processes.