Pressure & Temperature Charts

_______1015______ Isobars
Contours are lines connecting points of equal atmospheric pressure measured in hectopascals (hPa).

Cold front
The leading edge of a colder air mass, usually associated with cloud and precipitation, followed by decreasing temperatures.

Warm front
The leading edge of a warm air mass which commonly brings cloud and precipitation followed by increasing temperatures.

Stationary front
A stationary or slow-moving boundary between two air masses. Cloud and prolonged periods of precipitation are common.

Occluded front (or 'occlusion')
Occlusions form when the cold front of a depression catches up with the warm front, lifting the warm air between the fronts into a narrow wedge above the surface. Occluded fronts bring cloud and precipitation.