Col (meteorology)

It takes the form of a saddle where the air pressure is relatively higher than that of the low-pressure regions, but lower than that of the anticyclonic zones.

Such a pattern packs isotherms and moisture so that, at the point called Z, warm air is advected from the South (TI) while cold air comes from the North (PI);[2] then the flow spreads the airmass from one to the other, forming a stationary front.

Any other arrangement that permits confluence of the air flow leads to the formation of a col.[3] In any case, the col is always identified as an area of slack pressure.

[4] In the real atmosphere, highs and lows have rarely the same strength and thus equal wind flow pattern around them.

[5] In the anticyclonic col, the curvature of the high pressure area isobars is greater than that of the cyclonic flow.

Diagram of the position of the col between pressure highs and lows in the Northern Hemisphere.