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Tornado Formation Supercells
- 1. Lenna Connolly Science Speech Mr. Cooper
- 2. 2 A Tornado! Earth’s most destructive & violent storm.
- 3. 3 What is a tornado? A violently spinning column of air forming a vortex Wind is invisible so you need water vapor or dust & debris to see them
- 4. 4 Funnel Cloud Twisting column of air called a vortex Does not touch ground Can produce damage
- 5. 5 Tornado Statistics 400 to 500 feet wide 1,000 feet tall Winds are 112 miles per hour Most less than ten minutes in duration Only cover a few miles on the ground
- 6. Monster Tornadoes Miles wide Strongest winds ever measured Some 300 miles per hour Can last for more than an hour Can travel over 200 miles on the ground 6
- 7. 7 Tornado Alley There are many types of tornadoes, but I will be talking about the ones in the Midwest in an area called “Tornado Alley”
- 8. Supercell Largest, strongest, longest lasting thunderstorms They are huge rotating thunderstorms Create rain, hail, dangerous wind, flash floods & lightning and sometimes, tornadoes (up to 30% of the time) 8
- 9. 9 To understand how a tornado is formed, we must first understand Supercell thunderstorms and the conditions needed to create them.
- 10. 10 I will first talk about the basic elements, and then show you how they all fit together to form a tornado.
- 11. 11 Conditions 1. Warm moist air Gulf of Mexico 2. Cold air Canada and Polar regions 3. Hot air South Western desert 4. High winds of Jet Stream
- 12. 12 Dry Line Tornadoes form along the boundary where air masses meet. Colliding air masses at DRYLINE trigger severe storms which cause tornadoes to occur.
- 15. 15 Four Main Ingredients needed for Supercells 1. Wind Shear 2. Instability 3. Moisture 4. Lift
- 16. 16 Wind Shear Creates spinning columns of horizontal wind: Air moves at: different speeds different heights different directions
- 17. 17 Instability For a Supercell to develop you also need INSTABILITY Warm air rises upwards It is less dense than the surrounding atmosphere. Rises like a hot air balloon.
- 18. 18 Moisture and Latent Heat Warm moist air rises and cools. Water vapor condenses forming Clouds Condensation releases latent heat (energy) causing it to rise even higher forming updraft
- 19. 19 Updraft Sun warms ground, ground warms air Warm buoyant air rises, breaking through cooler air above Vapor condenses, releases heat, rises higher, creating an updraft
- 20. 20 Downdraft Updraft counterbalanced by downdraft Downdraft cooled air sinks Creates spiraling motion in updraft, needed for tornado
- 21. 21 Veering Winds Veering winds turn clockwise with height. Turning winds with height help thunderstorm develop its most essential component: THE MESOCYCLONE
- 22. 22 Mesocyclone and Wind Shear Wind shear (red) sets air spinning The Updraft (blue) tilts spinning air column upright The updraft starts rotating
- 23. 23 Wall Cloud Spinning layers of clouds Descends from Mesocyclone It is closer to Mesocyclone’s center rain-free Funnel cloud may form at center First stage of tornado formation
- 25. 25 What causes the funnel cloud to spin down creating a tornado is uncertain, but scientist have a theory.
- 27. 27 “Touching Down” TORNADO MATURITY: Mature at touch-down Warm, moist air from the ground continues to fuels it making it more powerful Can last for minutes or even an hour
- 28. 28 Tornado Losing Strength Loses strength when cold or dry air mixes with the hot air that was fueling the updraft (The moist warm air is its fuel) Tornado spins into a rope whipping the ground and disappears into the air
- 29. 29 Tornado Losing Strength As tornado dies, it tilts, becomes ropelike, speeds up, still destructive Whips ground as it deflates RFD that wrapped around mesocyclone to form tornado, eventually chokes off inflow of warm air (fuel) and kills it
- 30. 30 Summary Tornadoes are earth’s most destructive storms 3 out of 4 tornadoes happen in the United States Most tornadoes happen in the Midwest in Tornado Alley
- 31. 31 Summary Formed in Supercells - huge rotating thunderstorms Need Wind Shear, Instability, Moisture, and Lift Veering winds create essential component mesocyclone Scientists uncertain why tornadoes spin down
- 32. 32 In Conclusion Scientists know a great deal about the formation of tornadoes, but they are difficult to study. Once a tornado is gone, all they can study is the damage it left behind.
- 33. 33 The Fujita Scale estimates tornado intensity based on damage - Rated from F0 to F5.
- 34. 34 Before the National Weather Service started studying tornadoes, the average deaths a year, were 230 people. Today, it’s dropped into the 70’s.
- 35. 35 The more we learn, the better we can protect ourselves from the most violent storm in the world – A TORNADO!
- 36. 36
- 37. 37
Notas del editor
- Tropical air comes from the Gulf of Mexico. Hot, dry air from the desert. Where they meet is called the DRYLINE. This is where most tornadoes form.
- 1. The sun warm the ground. The ground warms the air above it. The hot, dry desert air traps or caps it. 2. It build up pressure.3. Eventually it breaks free forming an UPDRAFT resulting in thunderstorm within a cumulonimbus cloud
- This is a cumulonimbus cloud. We will talk about this later
- In this picture, winds are slower at the bottom level of atmosphere, but increase speed at higher level. Wind shear happens with winds at different speed, heights, and directions
- Warm air rises into cooler atmosphere, creating clouds. These different temperatures create INSTABILITY
- As warm moist air rises and cools, water vapor condenses forming clouds. This condensation releases latent (hidden) heat which is energy. This heats air, causing it to rise even higher forming an UPDRAFT
- WARM AIR RISES BECAUSE IT IS LESS DENSE AND IS BUOYANT CAUSING AN UPDRAFT.
- COOL AIR FALLS BECAUSE IT IS DENSER CREATING DOWNDRAFT
- VEERING WINDS TURN CLOCKWISE WITH HEIGHT. TURNING WINDS CREATE THE SUPERCELL’S MOST ESSENTIAL COMPONENT: THE MESOCYCLONE
- In the first picture you see rotating winds from WIND SHEAR. 2. The UPDRAFT tilts rotating air 3. until it is vertical.This is the MESOCYCLONE
- A Wall cloud lowers from the MESOCYCLONE. This area is rain free. A funnel cloud may form here. This is the first stage of the formation of a tornado
- This is another example of a wall cloud
- Scientists believe the RFD circles around the mesocyclone, tightens it, and stretches it down to the ground. Supercells rise to the top of the troposphere and can go no further, so the air spreads out into an anvil shaped cloud
- As the storm moves forward into the area where it has rained or hailed, there is no more warm, moist air to fuel the tornado. The tornado deflates and spins into a rope, whipping the ground and eventually disappears into the air.
- Dies = tilts, ropelike, speeds up, still destructive. Some scientists believe that the same RFD that births the tornado, squeezes it, choking it until it dies dead
- Scientists use the Fujita Scale to rate tornado intensity from an F0, the weakest, to F5 which is the strongest