Air Masses and Fronts

Air Mass Source Region

Fronts Cold Warm Occluded Stationary

Cold Front Winds Weather Temperature Rules of Thumb Southwest Shifting to Northwest after Frontal Passage Weather Thunderstorms Rainshowers Temperature Cooler and drier after frontal passage Rules of Thumb Southwest Wind Cumulus (puffy) clouds Falling Pressures Increasing cloudiness

Towering Cumulus

Cumulonimbus

Warm Front Winds Weather Temperature Rules of Thumb Southeast Shifting to Southwest Weather Rain, Drizzle, Possible Thunderstorm Fog (when ground is cool) Temperature Warm and Moist After Frontal Passage Rules of Thumb Southeast Wind Stratus (flat)clouds) Falling Pressures Increasing cloudiness, low ceilings, slow clearing after passage

Stratus a Common Warm Frontal Cloud

Stationary Front Winds Weather Temperature Rules of Thumb Northeasterly on cold air side, southeast on warm air side Weather Thunderstorm on Cold Air Side Temperature Minor variations across front Rules of Thumb Persistently poor weather STATIONARY FRONTS CAN LAST FOR DAYS OR WEEKS!!!

Occluded Front Winds Weather Temperature Rules of Thumb Southeast to south, after passage West to Northwest Weather Combination of Warm and Cold Fronts Rainshowers, Drizzle, Possible Thunderstorm Fog (when ground is cool) Temperature Change less significant Rules of Thumb Mixed bag of weather Low Pressures

Fronts on a Weather Chart