PRESENTATION OUTLINE
How do tornadoes form?
Most tornadoes form from thunderstorms. You need warm, moist air from the Gulf of Mexico and cool, dry air from Canada. When these two air masses meet, they create instability in the atmosphere. A change in wind direction and an increase in wind speed with increasing height creates an invisible, horizontal spinning effect in the lower atmosphere. Rising air within the updraft tilts the rotating air from horizontal to vertical. An area of rotation, 2-6 miles wide, now extends through much of the storm. Most strong and violent tornadoes form within this area of strong rotation.
Funnel cloud!!
a rotating funnel-shaped cloud forming the core of a tornado or waterspout.
A wall cloud!!
is the parent to a tornado. It's the rotating part of a thunderstorm that squeezes down a fast-spinning tornado, like an ice-skater pulling himself into a faster and faster spin.
The F Scale bridges the gap between the Beaufort Wind Speed Scale and Mach numbers (ratio of the speed of an object to the speed of sound) by connecting Beaufort Force 12 with Mach 1 in twelve steps. The equation relating the wind velocities (V in mph) with the F scale (F) is V = 14.1 * ((F+2) to the 1.5 power).
F1 on the F Scale is equal to B12 (73 mph) on the Beaufort scale, which is the minimum windspeed required to upgrade a tropical storm to a hurricane. F12 on the F Scale is equal to M1 (738 mph) on the Mach numbers. Though the F Scale itself ranges up to F12, the strongest tornadoes max out in the F5 range (261 to 318 mph).
It destroys everything in its path.
Kills livestock
Disrupts the food chain
1. The "Tri-State Tornado" killed 695 people and injured 2,027, traveling more than 300 miles through Missouri, Illinois and Indiana on March 18, 1925. It was rated an F5 at the top of the old Fujita scale (with winds of 260-plus mph).
05/11/1953
Force 5
Deaths114
Injured 597
Distance 28
The months with the greatest number of tornadoes overall are April, May, and June, but tornadoes can and do occur during any month of the year. Tornado seasons vary in different parts of the United States.
