Definition
A wind that flows downhill, caused by cold, dense air sliding down a sloped surface such as a mountainside, glacier, or elevated terrain under the pull of gravity. Katabatic winds typically form at night or during cold conditions when air in contact with high terrain cools, becomes heavier than the surrounding air, and drains downslope into valleys or lower ground. In some regions these winds can become very strong and persistent.
Plain English
A wind that runs downhill because cold air on a slope is heavier than the warmer air below, so gravity pulls it down toward lower ground.
Context Anchor
Pilots encounter katabatic wind in mountain, valley, coastal, and cold-region flying, especially near slopes after sunset or near glaciers.
Derivation
From the Greek 'katabatikos,' meaning 'going down' or 'descending.' The 'kata-' part means 'down,' which is a useful anchor: katabatic = downhill flow. Its opposite, anabatic, means 'going up.'
Why Pilots Care
Katabatic winds can produce unexpected gusts and shifts in wind direction near runways in hilly areas, affecting aircraft performance on takeoff and landing.
Analogy
Think of cold air like a slow, invisible liquid. When it forms on high ground, it can drain downhill into lower areas.
Grounding Statement
Picture cold air sitting on a mountain slope at night, getting heavier as it cools, and then spilling downhill like water finding the lowest path.
Intuition Check
Do not read katabatic wind as just any wind near mountains. It specifically means wind flowing downhill because cooled, heavier air is draining from higher ground.
Example Sentence 1
The pilot expected calm conditions at the valley airport but encountered a strong katabatic wind flowing down off the surrounding mountains shortly after sunset.
Example Sentence 2
After sunset, katabatic winds often develop along the slopes, bringing cooler air into the lower elevations.