Thunderstorms and Tornadoes

1. Thunderstorms and Tornadoes By: Karen Williams, Danielle Clark, and Alexa Caturay

2. Thunderstorms and Tornadoes • Thunderstorms and tornadoes are among the most destructive weather systems. • In this presentation we will discuss the causes and effects of these weather systems and what one can do to be prepared for them.

3. What are Thunderstorms? • Thunderstorms are storms with thunder, lightning, and usually heavy rain or hail. • While not as dangerous as other extreme weather conditions, thunderstorms can still inflict much damage.

4. What causes these storms? • For a thunderstorm to occur, the following ingredients must be present: • Moisture which forms clouds and rain. • Warm air, which is unstable and rises rapidly. • Lifts, which are breezes capable of lifting the air to form thunderstorms.

5. How do thunderstorms develop? • Thunderstorms develop in warm, moist air in • advance of eastward-moving cold fronts. These • thunderstorms often produce large hail, strong • winds, and tornadoes. Before thunderstorms develop, a change in wind direction and an increase in wind speed create an invisible spinning effect in the lower atmosphere.

6. How do thunderstorms develop? Rising warm air carries moisture up into cooler air where the moisture condenses and builds cumulus clouds vertically, thus creating a thunderhead. After a large cloud has built rain, hail, or other forms of precipitation usually begin to fall. This lasts anywhere from ten minutes to several hours depending on the severity of the storm. The storm will eventually dissipate with rain falling less intensely.

7. When and where are thunderstorms most likely to occur? Thunderstorms can occur at any time of the year, most of them occur on the afternoon during hot summer days. They are fairly common and occur all over the world.

8. Why are thunderstorms dangerous? • During a thunderstorm, even as it tapers down, lightning and flash floods can pose threats. • The other big threat posed by thunderstorms is the creation of tornadoes.

9. What are Tornadoes? • Tornadoes are the most violent of extreme weather conditions suffered on earth. They consist of rotating columns of air ranging in width from a few yards to more than two killometers, moving at destructively high speeds, usually accompanied by a funnel-shaped downward cloud.

10. What causes these storms? • Tornadoes are caused by violent thunderstorms. • An abrupt change in wind speed and direction as well as extreme instability in the weather patterns helps the formation of tornadoes. These conditions are usually found before a cold front. • The updrafts and downdrafts present in a thunderstorm create the spinning effect that makes tornadoes so dangerous.

11. What causes these storms?

12. Where and when are tornadoes most likely to occur? • Tornadoes can occur all over the world, however they are most likely to occur in the United States, east of the Rocky Mountains. An average 800 tornadoes are reported a year in this area and due to the frequency of them, it has been dubbed ‘Tornado Alley’. In Canada, most tornadoes occur in southern Ontario and Alberta, and in southeastern Quebec. • Prime tornado conditions are in the spring, in particular in late May. Most tornadoes happen in the mid or late afternoon. Tornadoes do not often occur in January or February.

13. TORNADO ALLEY: USA

14. Are tornadoes likely to happen here? • There have been few occurrences of tornadoes in the Windsor area. • The last tornado to hit Windsor occurred in 1974. It left 30 dead and many injured and caused a total of $500 000 worth of damage.

15. Are tornadoes likely to happen here? • Prior to this, a tornado occurred in 1946. It left 17 dead and many injured. It also caused a conservatively estimated $1.5 million in damage

16. Where else have tornadoes occurred? • The most recent tornado occurred on April 7th, 2005 in Mississippi. It was severe enough to cause extensive damage to homes, uproot trees, and topple telephone poles. A total of 19 tornadoes were reported between 6 a.m. and 2 p.m.

17. How dangerous are tornadoes? • Tornadoes are the most violent of storms. The potential of destruction caused by tornadoes depends on the Fujita tornado intensity scale.  The weakest on the scale, a zero (0), can cause branches and windows to break and shallow rooted trees to be pushed over with winds reaching up to 118 km per hour.   The most violent type of tornado is 5 on the f-scale.  This type of tornado causes cars to be thrown as far as 100 meters, houses to be lifted off of their foundations and trees to be uprooted with winds reaching up to 513 km per hour.    

18. How dangerous are tornadoes? • Fujita Tornado Scale F-0: 40-72 mph. Chimney damage occurs and tree branches are broken

19. How dangerous are tornadoes? • Fujita Tornado Scale F-1: 73-112 mph. Mobile homes are pushed off of their foundation or overturned.

20. How dangerous are tornadoes? • Fujita Tornado Scale F-2: 113-157 mph. Considerable damage occurs, including the demolition of mobile homes and uprooting of trees.

21. How dangerous are tornadoes? • Fujita Tornado Scale F-3: 158-205 mph. The walls and roofs of buildings are destroyed, trains overturned, and cars picked up and thrown.

22. How dangerous are tornadoes? • Fujita Tornado Scale F-4: 206-260 mph. Extnsive damage is done with the well constructed walls and roofs of buildings completely leveled.

23. How dangerous are tornadoes? • Fujita Tornado Scale F-5: 260-318 mph. Extreme damage is done. Homes can be lifted from their foundations and carried considerable distances, and automobiles thrown more than 100m.

24. Tornado Safety. • When a tornado is coming, you have only a short amount of time to make life-or-death decisions. Advance planning and quick response are the keys to surviving a tornado. • BEFORE • Conduct tornado drills.Designate an area as a shelter, and practice having everyone go there in response to a tornado threat. • Make an emergency supply kit that includes: • Flashlight and extra batteries • Portable, battery-operated radio and extra batteries • First aid kit and manual • Emergency food and water • Non-electric can opener • Essential medicines • Cash and credit cards • Sturdy shoes

25. Tornado Safety. • Learn these tornado danger signs: • An approaching cloud of debris can mark the location of a tornado even if a funnel is not visible. • Before a tornado hits, the wind may die down and the air may become very still. • Tornadoes generally occur near the trailing edge of a thunderstorm. It is not uncommon to see clear, sunlit skies behind a tornado.

26. Tornado Safety. • DURING • If at home: • Go at once to a windowless, interior room; storm cellar; basement; or lowest level of the building. • If there is no basement, go to an inner hallway or a smaller inner room without windows, such as a bathroom or closet. • Get away from the windows. • Go to the center of the room. Stay away from corners because they tend to attract debris. • Get under a piece of sturdy furniture such as a workbench or heavy table or desk and hold on to it. • Use arms to protect head and neck. • If in a mobile home, get out and find shelter elsewhere.

27. Tornado Safety. • DURING • If at work or school: • Go to the basement or to an inside hallway at the lowest level. • Avoid places with wide-span roofs such as auditoriums, cafeterias, large hallways, or shopping malls. • Get under a piece of sturdy furniture such as a workbench or heavy table or desk and hold on to it. • Use arms to protect head and neck. • If outdoors: • If possible, get inside a building. • If shelter is not available or there is no time to get indoors, lie in a ditch or low-lying area or crouch near a strong building. Be aware of the potential for flooding. • Use arms to protect head and neck.

28. Tornado Safety. • DURING • If in a car: • Never try to outdrive a tornado in a car or truck. Tornadoes can change direction quickly and can lift up a car or truck and toss it through the air. • Get out of the car immediately and take shelter in a nearby building. • If there is no time to get indoors, get out of the car and lie in a ditch or low-lying area away from the vehicle. Be aware of the potential for flooding.

29. Tornado Safety. • AFTER • Help injured or trapped persons. • Give first aid where needed. • Don't try to move the seriously injured unless they are in immediate danger of further injury. • Call for help. • Turn on radio or television to get the latest emergency information. • Stay out of damaged buildings. Return home only when authorities say it is safe. • Use the telephone only for emergency calls. • Clean up dangerous spills immediately. Leave the building if you smell gas or chemical fumes. • Take pictures of the damage both to the house and its contents for insurance purposes.

30. What happens Next? • Eventually all storms dissipate. They either move on to another region, or lose all of their energy and disperse. Rain slows then stops, clouds disappear, and winds cease.

31. Trivia! • Where are tornadoes most common? • Although tornadoes form all over the world, they are more frequent and stronger in US.

32. Trivia! • What is a tornado that forms over water called? • A tornado that forms over warm water is called a waterspout. The water in the spout comes from condensation, not from the water below.

33. Trivia! • What is a tornado that forms over a desert called? • A tornado that forms over a desert is called a dust devil.

34. Trivia! • How fast do most tornadoes spin? • The average forward speed of a tornado is 30 to 40 mph but can go as fast as 70mph and has rotational speed that can be more than 300mph.

35. Trivia! • What was the worst tornado recorded? • The worst series of tornadoes in history was on March 18, 1925. About 689 people were killed in Missouri, Illinois and Indiana.

36. Trivia! • In which direction do most tornadoes spin? • Usually in the northern atmosphere tornadoes turn counter-clockwise. In the southern hemisphere, tornadoes usually turn clockwise.

37. Trivia! • How do we know how severe a tornado is? • Scientists can’t rate or know how strong a tornado is until after it is over

38. THANK YOU!

39. Credits • Information and Pictures: • http://www.fema.gov/hazards/tornadoes/tornadof.shtm • http://www.cnn.com/2005/WEATHER/04/06/tornadoesmississippi • http://www.exn.ca/Stories/1999/05/04/54.asp • www.noaa.gov/tornadoes.html • http://www.gettyimages.com • Songs and Sounds: • Microsoft PowerPoint Sound Clip Gallery • ‘Rainy Days and Mondays’ – The Carpenters • ‘Raindrops Keep Falling’ – BJ Thomas • ‘I Can See Clearly Now’ – Johnny Nash