Shop Windows to the Universe

The Spring 2011 issue of The Earth Scientist is focused on modernizing seismology education. Thanks to IRIS, you can download this issue for free as a pdf. Print copies are available in our online store.
A weak tornado that was seen in Southeast Colorado.
Click on image for full size
Courtesy of University Corporation for Atmospheric Research, Photo by Linda Lusk

Sizes of Tornadoes

Tornadoes come in three different sizes, each with different characteristics. The three sizes are: weak, strong, and violent. Their size is based on how large the tornado is as well as the time that the tornado lasts and how it compares to the Enhanced Fujita Scale.

A weak tornado is the most common type of tornado and makes up 69% of all tornadoes. The least number of deaths happen from this type of tornado, and the longest they can last is a little more than 10 minutes. Winds within this category of tornado are less than 100 mph (161 kph). Weak tornadoes are part of the first two categories of the Fujita Scale (F0 & F1). Damage from a weak tornado can include broken tree branches and peeling off the roofs from houses and buildings.

Strong tornadoes include 29% of all tornadoes. This type of tornado causes 30% of all deaths from tornadoes. Wind speeds for strong tornadoes are between 110-205 mph (177-330 kph). These tornadoes can last 20 minutes or even longer. Demolished mobile homes and overturned trains are part of the damage that could happen from a strong tornado.

While a violent tornado is the least common, it is very deadly. Violent tornadoes make up 70% of all tornado deaths. This type of tornado can last over an hour. Wind speeds for violent tornadoes are typically greater than 205 mph (330 kph). A violent tornado is part of the last two categories on the Fujita Scale (F4 & F5). These tornadoes can do a lot of damage, including throwing cars and picking up well built houses and carrying them for miles.

Last modified June 11, 2008 by Vanessa Pearce.

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.

Windows to the Universe Community

News

Opportunities

You might also be interested in:

Traveling Nitrogen Classroom Activity Kit

Check out our online store - minerals, fossils, books, activities, jewelry, and household items!...more

Wind

Wind is moving air. Warm air rises, and cool air comes in to take its place. This movement creates different pressures in the atmosphere which creates the winds around the globe. Since the Earth spins,...more

Rainbows

Rainbows appear in the sky when there is bright sunlight and rain. Sunlight is known as visible or white light and is actually a mixture of colors. Rainbows result from the refraction and reflection of...more

The Four Seasons

The Earth travels around the sun one full time per year. During this year, the seasons change depending on the amount of sunlight reaching the surface and the Earth's tilt as it revolves around the sun....more

Research Aircraft

Scientists sometimes travel in specially outfitted airplanes in order to gather data about atmospheric conditions. These research aircraft have special inlet ports that bring air from the outside into...more

Anemometer

An anemometer is a weather instrument used to measure the wind (it can also be called a wind gauge). Anemometers can measure wind speed, wind direction, and other information like the largest gust of wind...more

Thermometer

Thermometers measure temperature. "Thermo" means heat and "meter" means to measure. You can use a thermometer to measure the temperature of many things, including the temperature of...more

Weather Balloons

Weather balloons are used to carry weather instruments that measure temperature, pressure, humidity, and winds in the atmosphere. The balloons are made of rubber and weigh up to one kilogram (2.2 pounds)....more

Windows to the Universe, a project of the National Earth Science Teachers Association, is sponsored in part by the National Science Foundation and NASA, our Founding Partners (the American Geophysical Union and American Geosciences Institute) as well as through Institutional, Contributing, and Affiliate Partners, individual memberships and generous donors. Thank you for your support! NASA AGU AGI NSF