Definition
A neutral region on a weather map between two areas of high pressure and two areas of low pressure, where the pressure pattern resembles a saddle. Winds in a col are typically light and variable, and weather conditions are often unsettled.
Plain English
A col is a calm, in-between zone on a weather chart sitting between two highs and two lows, where the air doesn't have a strong push in any one direction.
Context Anchor
Seen in aviation weather discussions, surface analysis charts, and forecast explanations of weak or variable wind patterns.
Derivation
From the French 'col,' meaning 'neck' or 'pass' -- the same word used for a low pass between two mountain peaks. On a weather map, the pressure pattern looks similar: a low saddle sitting between higher and lower pressure areas on either side.
Why Pilots Care
Weather inside a col is often hard to predict. Winds are light and shifty, visibility can change, and thunderstorms or fog may form because the air isn't being steered cleanly by a pressure gradient.
Analogy
Think of a low pass between hills. Air can sit there or move weakly because it is not being strongly pulled in one clear direction.
Intuition Check
Do not read Col as “column” or “colonel.” In aviation weather, a col is a pressure-pattern area between highs and lows.
Example Sentence 1
The forecaster pointed out a col over the region, warning that winds aloft would be light and direction would be unreliable.
Example Sentence 2
We routed around the col to avoid the stable air and reduced visibility it often brings.