Tornado observed by the VORTEX-99 team on May 3, 1999, in central Oklahoma. Note the tube-like condensation funnel, attached to the rotating cloud base, surrounded by a translucent dust cloud.
Click on image for full size
Courtesy of NOAA
Before 1971, there was no way to categorize tornadoes by their strength. Without a standard
system to rank tornadoes, there was no way to keep an accurate storm
record; everybody had their own idea of how strong the storm was. In 1971, T.
Theodore Fujita, a professor at the University of Chicago, came up with a
system that equated wind speed
with tornado damage. This original Fujita tornado scale had six categories from F0 to F5.
A new scale for rating the strength of tornadoes
became operational on February 1, 2007 and it is called the Enhanced Fujita Scale.
The Enhanced Fujita Scale or EF Scale has six categories from zero to five, with EF5 being the highest degree of damage. The Scale was used the first time as three separate tornadoes took place in central Florida early on February 2, 2007. These tornadoes destroyed many houses and businesses and killed at least 21 people. And these tornadoes were only rated EF3 tornadoes.
The first time the EF5 measurement was recorded was in the Greensburg, KS tornado that occurred on May 4, 2007. The tornado was estimated to be 1.7 miles in width and traveled for over 22 miles. Its winds reached 205 mph. The city of Greensburg was virtually destroyed and 12 people lost their lives that day. Tornado sirens were sounded in Greensburg twenty minutes before the tornado hit, certainly saving countless lives. Still, much better tornado forecasting is needed to give even earlier warnings.
Scientists have to figure out how strong a tornado was after it is over.
Because the scale is based on the damage caused by it, they can't predict
how strong a tornado would be before it strikes.
Shop Windows to the Universe Science Store!Cool It!
is the new card game from the Union of Concerned Scientists that teaches kids about the choices we have when it comes to climate change—and how policy and technology decisions made today will matter. Cool It! is available in our online store
You might also be interested in:
What types of instructional experiences help K-8 students learn science with understanding? What do science educators teachers, teacher leaders, science specialists, professional development staff, curriculum designers, school administrators need to know to create and support such experiences?...more
Tornadoes form from severe thunderstorms. They have a very high energy density which means that they are very destructive to a small area. They also don't last very long which makes them hard to study....more
The short duration and complicated nature of tornadoes make them nearly impossible forecast. Meteorologists don't really know the specifics of how they form, but they do know what atmospheric conditions...more
Tornadoes are very destructive, so it's important to know when one may form so you can take shelter. Forecastors at the National Weather Service are always on the lookout for developing storms. Even though...more
Tornadoes come in three different sizes, each with different characteristics. The three sizes are: weak, strong, and violent. Their size is dependent not only on their physical width but is part of the...more
Sound travels in waves. These waves have both a frequency and an amplitude. The frequency is measured in hertz, which is one wave cycle per second. A cycle is a repeated pattern of positive and negative...more
Storms chasers are different than storm spotters. Chasers travel around Tornado Alley looking for severe storms and tornadoes. This area in the Great Plains is the best for chasing. Besides having a lot...more
A tornado is the most destructive force in nature; that doesn't mean it has the most energy. Thunderstorms which produce tornadoes can have 40,000 times as much energy as a tornado! Tornadoes are so destructive...more