katabatic

Katabatic wind is a drainage wind that flows downslope off a high plateau, mountain range, or ice sheet, driven by gravity and enhanced by radiative cooling of the surface. The term katabatic comes from the Greek katabatikos, meaning falling down.

The mechanism begins with radiative cooling of air near the surface, typically on clear nights. Cooler, denser air near the ground becomes heavier than the air aloft, causing it to flow downslope under gravity. The flow accelerates as it descends and is shaped by the slope, surface roughness, and obstacles. Friction near the ground slows the very lowest layers, while the upper part of the flow remains driven by the pressure and temperature gradient. The result is a strong, downslope wind that can persist for several hours, especially along steep or smooth surfaces such as snow or ice.

Katabatic winds are common in polar regions and high mountains. They occur on Antarctica and Greenland, along sea coasts where interior cold air drains toward the ocean, and over glacier valleys. They may produce very cold conditions at valley floors, contribute to temperature inversions, and influence local weather and aviation operations. In some contexts, they interact with larger synoptic winds, modifying wind speed and direction near the surface.

Anabatic winds are the opposite phenomenon, consisting of upslope flows driven by daytime heating. Katabatic flows are a related category of gravity-driven winds that illustrate how surface cooling and terrain shape local atmospheric motion.