2. THUNDERSTORMS, LIGHTNING and TORNADOES pcooke 5/10/03

3. FORMATION OF A CUMULONIMBUS Created by large sections of warm, moist air rising into cool, dry air. A cold front or convection in the atmosphere typically causes the warm air to rise and water vapor to condense. 3 stages: cumulus, mature, and dissipating.

4. Cumulus Stage No lightning or chance of tornado formation during this stage. Heat from condensing water vapor in the cloud helps to fuel expanding and rising air. The upward-moving air in this stage can approach speeds of 160 km/hr.

6. Mature Stage As the warm moist air mass rises, the water vapor cools. The water vapor condenses, (which releases more heat) saturates the cloud and produces torrential rains. The falling rain pushes and pulls air downward with it, and the storm develops regions of fast moving downdrafts. Simultaneously, rising warm air and falling colder air, causes large amounts of static electricity to be generated.

8. Mature Thunderstorms Large, mature thunderstorms can… Produce precipitation at astonishing rates, up to 36cm/hr. This causes local flooding. Produce precipitation at astonishing rates, up to 36cm/hr. This causes local flooding. Create hailstones as large as grapefruits! Ouch! Create hailstones as large as grapefruits! Ouch! Generate tremendous electrical power and intense lightning. Generate tremendous electrical power and intense lightning. Produce tornadoes with devastating swirling winds Produce tornadoes with devastating swirling winds

9. Dissipating Stage Downbursts of high speed wind may occur. All air within the storm has become cooler than the air outside of the storm. If deprived of its energy source of warm, moist air, the storm soon splits into a series of disorganized layers of clouds…and the storm is finished….

13. LIGHTNING! The rapid movement of electric energy from one part of a cloud to another or to the ground. The rapid movement of electric energy from one part of a cloud to another or to the ground. Occurs when positive and negative charges build up in different regions of a cumulonimbuscloud. Occurs when positive and negative charges build up in different regions of a cumulonimbus cloud. Large raindrops and hail become charged by friction as they fall through the cloud. Large raindrops and hail become charged by friction as they fall through the cloud. The top of the cloud becomes positively charged. The top of the cloud becomes positively charged. The bottom of the cloud becomes negatively charged The bottom of the cloud becomes negatively charged

15. 6000 strikes per minute worldwide! Lightning is responsible for more deaths annually than tornadoes and hurricanes combined. Lightning is responsible for more deaths annually than tornadoes and hurricanes combined. It causes fires and is often responsible for urban blackouts It causes fires and is often responsible for urban blackouts Florida has the most in the US. Why? Florida has the most in the US. Why?

17. Lightning is very hot, nearly 5 times as hot as the surface of the sun! Thunder is the sound of rapidly expanding air as it heats to a very high temperature in a fraction of a second. A low rumble is caused by distant lightning. A sharp crack indicates a nearby strike.

18. FLASH……….BOOM! Light from a lightning bolt travels very fast about 670,000,000 miles/hour Light from a lightning bolt travels very fast about 670,000,000 miles/hour Sound travels much more slowly about 761miles/hour (13 miles/minute or.2 miles/second) Sound travels much more slowly about 761miles/hour (13 miles/minute or.2 miles/second) This is why you see the flash before the thunder is heard. This is why you see the flash before the thunder is heard. The smaller the interval between seeing lightning and hearing the sound of thunder, the closer you are to the lightning. The smaller the interval between seeing lightning and hearing the sound of thunder, the closer you are to the lightning.

19. What is the approximate distance of a thunderstorm when you note a 5 second delay between the flash of the lightning and the sound of the thunder? Answer: 5 seconds .2 miles/second = 1 mile

20. Lightning Safety The six most common dangerous activities associated with lightning strikes, in order, are: Work or play in open fields. Work or play in open fields. Boating, fishing, and swimming. Boating, fishing, and swimming. Working on heavy farm or road equipment. Working on heavy farm or road equipment. Playing golf. Playing golf. Talking on the telephone. Talking on the telephone. Repairing or using electrical appliances. (NWS) Repairing or using electrical appliances. (NWS) If caught in the open during a strike and the hair on your head begins to stand on end go inside the nearest building. If no shelter is available, crouch down immediately in the lowest possible spot, keep your feet on the ground. (DO NOT LIE DOWN. ) If caught in the open during a strike and the hair on your head begins to stand on end go inside the nearest building. If no shelter is available, crouch down immediately in the lowest possible spot, keep your feet on the ground. (DO NOT LIE DOWN. )

21. Treatment for Electrocution by lightning Check breathing and pulse. Check breathing and pulse. Call 911-send for help Call 911-send for help Perform mouth-to-mouth resuscitation. Perform mouth-to-mouth resuscitation. Apply cardiopulmonary resuscitation. Apply cardiopulmonary resuscitation. Only about 10 percent of those struck by lightning will die. Only about 10 percent of those struck by lightning will die.

22. Warm Up 5/11/12 1. What are some of the factors that cause thunderstorms? 2. Describe how lightning forms. 3. What type of cloud is responsible for thunderstorms? 4. If there is 15 seconds between the flash of light and the crack of the thunder, how far away is the lightning?

23. 400 Tornadoes in a week! Tornadoes are violent winds that rotate rapidly around an area of low air pressure. Tornadoes are violent winds that rotate rapidly around an area of low air pressure. Called funnel clouds before they reach the surface of Earth. Called funnel clouds before they reach the surface of Earth. May form during the mature stage of the most violent thunderstorms. May form during the mature stage of the most violent thunderstorms.

24. Cause much damage when their high velocity winds and twisting motion destroys objects in their path. Winds may reach 250 mi/hr but often are less than 90 mi/hr. Tornadoes are seen most often in the central, Southeastern, and Midwestern parts of the U.S.

31. Formation of a Tornado by updraft tilting of wind shear near the ground.

33. Bibliography http;//www.nssl.noaa.gov/ National Weather Service- Severe Storms National Oceanic and Atmospheric Administration arizonalightning.com- Jacobo Insogna 2002 stormwatch.com 5/8/03 Dan Lloyd Photography -1996 Webshots.com, 5/6/03 University of Akron Ohio The weather channel

34. Write a PARAGRAPH on the formation of thunderstorms, lightning, and tornados. Write a PARAGRAPH on the formation of thunderstorms, lightning, and tornados. –You can include cloud types, factors that affect each of these, places they occur most/least, etc.