Warm Up Chapter 20

2. Warm Up Chapter 20 • What kind of temperature or weather are the following fronts going to bring? • Cold front • Warm front • Occluded front • Stationary front • Draw the symbols for the following fronts. • Cold front • Warm front • Occluded front • Stationary front

3. 20.3: Thunderstorms and Tornadoes • Section 20.3 - Agenda • Thunderstorms • - Lightning • Tornadoes • Formation • Effects • Predicting • Watches and Warnings

4. Thunderstorms • Form in warm, moist, unstable air • These conditions form cumulonimbus clouds • Consist of one or more Cells vis2004

5. Thunderstorm Life Cycle 1. Cumulus stage – Moist warm air rises forming a cumulus cloud. The rising air is called an updraft. And updraft prevents precipitation from reaching the ground. vis2004

7. Thunderstorm Life Cycle 2. Mature stage – The precipitation becomes heavy enough to fall through the updraft and reach the ground. The falling precipitation creates a downdraft. vis2004

10. Thunderstorm Life Cycle 3.Dissipating stage – The downdraft weakens the updraft, eventually cutting off the supply of moist air rising into the cloud. The cloud begins to evaporate. vis2004

12. Thunderstorm Locations • Often form along fronts where warm air meets cold dry air and then rises. • Supercells are very strong single-cell thunderstorms.

13. End…

15. Squall Lines are lines of storms hundreds of miles long

16. Lightning • Huge discharge of electricity

18. Heats the air to more than 25,000 degrees Celcius. • Causes air to expand rapidly = thunder • Since light travels much faster than sound, you see lightning first, hear thunder later

19. Between Clouds Lightning Strikes

21. Cloud to Ground

23. Tornadoes • Violently rotating column • ofair • Usually touches the ground • Forms when a thunderstorm has an updraft called a mesocyclone vis2006

28. Tornadoes • Damage path can be a 100 feet, up to 1 mile wide • Measured with “Fujita” • scale • Predicted and tracked • using Doppler Radar