Definition
In meteorology, a classification describing an air mass that originates over high-latitude regions, typically between roughly 60° latitude and the polar circles. Polar air is cold and relatively dry at its source, and is further subdivided into continental polar (cP), forming over cold land areas, and maritime polar (mP), forming over cold ocean waters.
Plain English
Air that formed up near the top or bottom of the globe, where it's cold. When this cold air drifts down into the United States or other mid-latitude areas, it brings cooler, often drier weather with it.
Context Anchor
Seen in weather and air mass discussions when describing where an air mass formed and what kind of temperature it is likely to bring.
Derivation
From the Greek 'polos', meaning 'axis' or 'pivot' — the points the Earth rotates around. 'Polar' simply means 'belonging to the poles', so polar air is air that was sitting near one of the Earth's poles long enough to take on the temperature and moisture of that region.
Why Pilots Care
Polar air masses often trigger cold fronts, lower temperatures, and icing risks that affect aircraft performance, fuel planning, and route selection.
Grounding Statement
If a broad area of air sits over a cold northern land or ocean area, it can take on that cold character and later carry it across your route.
Intuition Check
Polar does not mean the air came exactly from the North Pole or South Pole. In this context, it means the air formed in colder high-latitude regions and has cold-air characteristics.
Example Sentence 1
A continental polar air mass moved south from Canada overnight, dropping temperatures and clearing the skies across the region.
Example Sentence 2
The forecast called for a polar air mass to bring clear skies and strong northerly winds behind the front.