1. Midlatitude Cyclones (Storms) Extratropical cyclone or wave cyclone or frontogenesis or storm Low pressure area with counter-clockwise circulation. Atmosphere collects water as water vapor in evaporation from oceans, lakes. It is returned via precipitation, often caused by storms.

2. Storms Center of intense low pressure with cyclonic circulation and resultant precipitation. Midlatitude Cyclone Hurricane Tornadoes Not thunderstorms, no cyclonic motion.

3. Cyclogenesis in Action: Mid-latitude (extratropical) cyclones

4. Air Masses Definition: volume of air with same temperature and humidity characteristics Source Regions: where air masses come from. Classification: warm or cold, moist or dry

5. Air Masses Affecting North America

6. Frontogenesis

9. Occluded Front : The Death of a Storm

10. Occluded Front

11. Weather Maps

12. Today’s Weather Map

13. Storm Tracks: North America Actual Storm Tracks (1991) Storms (Storm Tracks) generally travel from West to East in North America all year They shift North in summer & South in Winter Average Storm Tracks Moving West To East

14. Midlatitude Cyclone Characteristics Motion: these storms move across the midlatitudes at about 30 m.p.h. from west to east as they rotate once around a low pressure center. Size: roughly 1,000 miles in diameter, the largest of storms Lifespan: 3-6 days to develop, 3-6 to dissipate Pressure: center roughly 990-1000 mb (1-2 % drop)