Definition
A region of the atmosphere in which the barometric pressure is lower than that of the surrounding area; a low-pressure area.
Plain English
An area where the air pressure is lower than the air pressure around it. Pilots and weather forecasters call this a 'low.'
Context Anchor
Seen in weather briefings, surface weather charts, and discussions of low-pressure weather systems.
Derivation
From Latin 'deprimere,' meaning 'to press down.' In weather, the air in this area has lower pressure, as if it has been 'pressed down' below the surrounding pressure level.
Why Pilots Care
Depressions create strong winds, turbulence, low ceilings, and reduced visibility that directly affect route selection, altitude, and go/no-go decisions.
Grounding Statement
Picture a broad area on a weather map where the air pressure is lower than nearby areas, and the surrounding air is moving toward it.
Intuition Check
Depression does not mean sadness here. In aviation weather, it means a low-pressure area that can affect flying conditions.
Example Sentence 1
The forecaster noted a deepening depression moving across the region, bringing lower ceilings and rain.
Example Sentence 2
Near the center of the depression the winds shifted and visibility dropped, forcing the flight to divert to an alternate airport.