1. Tornadoes & Hurricanes BFRB – Pages 125 - 129

2. Today, you will learn… • What hurricanes and tornadoes are • How they form • How society should prepare for them to reduce loss of life and property damage

3. Tornadoes – Some Facts… • They are funnel shaped columns of spiraling winds that extend down to the ground from the base (bottom) of a cloud • The visible funnel is made by water droplets (clouds), dust and debris getting caught up in the wind and spiraling around in the funnel They usually last about 10 minutes or less but can sometimes last for hours. • Tornadoes are rated on the Fujita scale F0 (weakest) – F6 (severe) • An F6 is very rare, and can have wind speeds up to 318 mph

4. Tornadoes – How They Form • Form from very powerful thunderstorms (cumulonimbus clouds) • In the US, they are most common in spring and early summer because of cold temperatures in Canada and warmer temperatures in the Gulf of Mexico. • Tornadoes can occur anywhere in the US but most of them occur in the center of the country in an area called “tornado alley”

5. This area of the US is known as “tornado alley” Why do most tornadoes in the US happen here in “tornado alley”?

6. Cool, dry, dense air comes down from Canada This is a continental polar air mass “cP” Warm, moist, less dense air comes up from the Gulf of Mexico This is a maritime tropical air mass “mT”

7. How does the tornado funnel form? • The 2 air masses meet at a front and the cool dense air pushes the warm less dense air up very quickly creating a horizontal tube of swirling air – think of a roll of toilet paper. • Then, this horizontal tube of swirling air may be tilted toward the vertical by some sudden updrafts of air. • This turns the spinning tube of air into a vertical funnel cloud which eventually builds strength and speed and turns into a tornado • Here is an animation…. http://www.britannica.com/thunderstorms_tornadoes/ocliwea124v4.html

8. Tornadoes – How they cause damage… • Tornadoes are especially dangerous because it is so difficult topredict where and when they will form • Damage is usually along a narrow path where the tornado traveled • Most fatalities (deaths) are caused by flying debris • High winds cause severe property damage

9. And now, some very cool pictures of tornadoes…

12. NEW YORK TORNADOES!

13. Tornadoes will pick up dust and debris from the ground when they “touch down” – this creates a wider swirl at the bottom of the tornado

16. Yes, tornadoes are very cool and interesting… But, they can also be very deadly to people and costly to the economy. What should people do to prevent loss of life and damage to structures?

17. A Government or Public emergency preparedness plan for tornadoes should consist of… • Warning system – TV/Radio/Internet/Sirens • Emergency shelters for people made homeless by the storm • Building/Construction codes that minimize damage – ex – no mobile homes or weakly built structures

18. A Family/Personal emergency preparedness plan for tornadoes should consist of… • Where to go? Basement/storm cellar or an interior room with no windows like a bathroom or closet • What to have?Bottled water/canned food/battery powered radio/flashlight • What to do? Stay put until they announce that the danger has passed

19. Hurricanes – How they form • Huge tropical low pressure systems that get their energy from the tremendous amount of warm ocean water that is evaporated and condensed inside the storm • Hurricanes MUST form over open warm ocean water (WARM WATER = FUEL FOR HURRICANE) • Atlantic Ocean Hurricanes form over the warm water off of the West Coast of Africa and travel West across the Atlantic via the trade winds. • Since the warm water is where it gets its energy from, hurricanes weaken as they pass over land or colder water

20. Hurricanes – Some facts • Since hurricanes are extreme low pressure storms, the winds blow in towards the center of the storm, and it spins counter-clockwise (in the Northern Hemisphere) • A “tropical storm” is designated a “hurricane” when its winds reach 74 mph (and vice versa). • Hurricanes are classified by the Saffir-Simpson Scale as Category 1 (weakest) – Category 5 (strongest) • On average, hurricanes are 400 miles wide • The eye of the hurricane is the center where there are no clouds or precipitation and the weather is generally calm • All hurricanes are named in each ocean in alphabetical order, with alternating male and female names

21. Hurricanes, Typhoons and Cyclones are all the SAME THING!!! • Different Ocean = Different Name • Atlantic & East Pacific = Hurricane • Indian & South Pacific = Cyclone • West Pacific = Typhoon

22. Hurricanes – How they cause damage… • The three parts of a hurricane that cause the most damage are storm surge, high winds and intense precipitation • Storm surge is the term used for the water that a hurricane blows onto the shore, causing severe flooding and extreme property damage • Most fatalities (deaths) are caused by people drowning in the storm surge (many foolish people do not evacuate areas when told to do so)!! • Storm surge is what caused the flooding in New Orleans and the Gulf Coast during Katrina

24. And now, some very cool pictures of hurricanes…

25. The “eye” of the hurricane is the center portion where there are no clouds

28. This is a picture of an eyewall of a hurricane!!! The eyewall surrounds the calm eye and is the most dangerous part of a hurricane with the highest winds and most intense precipitation.

30. Hurricane Katrina – August 29th, 2005

31. Hurricane damage can range from broken windows to complete demolition of buildings. Until Katrina, Andrew in 1992 was the costliest hurricane for the USA with a price tag of over 20 BILLION dollars! Katrina is now reaching a cost of 200 BILLION DOLLARS!!!!

33. Yes, hurricanes are very cool and interesting… But, they can also be very deadly to people and costly to the economy. What should people do to prevent loss of life and damage to structures?

34. A Public emergency preparedness plan for hurricanes should have • Warning system – TV/Radio/Internet • Evacuation routes and signs so people can get out before the storm surge. • Emergency shelters for people to go to if they can’t evacuate or they are made homeless by the storm • Building/construction codes that minimize damage – ex – no mobile homes/weakly built structures • Emergency equipment/ supplies ready to come in as soon as the storm is over.

35. A Family/Personal emergency preparedness plan for hurricanes should consist of… • Where to go? Evacuate the area if you are in the storm surge warning area • What to have? Bottled water/canned food/battery powered radio/flashlight/cash/ emergency contact numbers/extra clothes • What to do? Board up the windows of your home to minimize damage Stay evacuated until given the OK by the authorities to return