Meteorology Air Masses & Fronts

Reference From the Ground Up Chapter 6.6 & 6.7: Air Masses & Fronts Pages 140 - 147

Introduction Giant air masses move around with the winds and rotate around pressure systems to bring different weather to areas. It’s important to know what types of air masses and fronts exist, how they form, and what kind of weather they will cause

Outline Air Masses Fronts

Air Masses Large section of troposphere with uniform properties of temperature and moisture in the horizontal May be several thousand miles across Takes on properties of surface over which it forms (known as Modification)

Classifications Classifications Continental Dry c Maritime Moist m Arctic Cold A Polar Moderate P Tropic Warm T Main types in North America in winter = cA, mA, mP Main types in North America in summer = mA, mP, mT

Air Masses Cold Air Mass Warm Air Mass Stability Unstable Air Turbulence Turbulent Smooth Visibility Good Poor Clouds Cumulus Stratus, Fog Precipitation Showers, Hail, Thunderstorms Drizzle

Fronts Transition zone between two air masses Cold Front Warm Front Slope Steep 1:50 Shallow 1:200 Weather Severe (unstable) Mild (stable) Clouds Cumulus Stratus Winds Veer Precipitation Showers Steady, Storms Temperature Cools Warms

Fronts Cold Front Leading edge of advancing cold air mass Faster the front, the more severe the thunderstorm

Fronts Warm Front Trailing edge of retreating cold air mass Indicated by high to low stratus clouds

Other Fronts Stationary Front Occluded Front (AKA Occlusion) Cold air neither advancing nor retreating Occluded Front (AKA Occlusion) Cold front overtakes warm front, lifts warm air up Trowal (Trough of Warm Air Aloft) Warm air lifted by occluded front

Next Lesson 4.7 – Meteorology Precipitation, Fog & Thunderstorms From the Ground Up Chapter 6.8, 6.9: Pages 147 - 154