1. What particular areas and regions are tornadoes attracted to?
2. What controls the intensity of a tornado?
3. Is their a particular balance of elements that are necessary for such a large tornado to form?
Areas of interest for students usually include size, frequency, locations and causes. I found two articles that I thought may answer some of these inquiries for students.
My first article reports that with tornadoes being the most lethal wind-related disasters in the world, on an average, about 800 tornadoes are reported in the United States yearly. Although tornadoes are no more frequent in North America than any other industrialized region in the middle latitude, the intensity of these storms is more severe. Tornadoes usually develop within intense thunderstorms classified as "Super cell Thunderstorms."
In North America, these atmospheric conditions develop in late winter in central gulf coast states, moving slowly northwest during the months of March and April. May is the peak month for tornadoes in the southern plains and the upper Midwest and Great Lakes region suffer mostly in the summer months. In a 24 hour period, 60% of tornadoes hit between noon and sunset, 21% from sunset to midnight and 19% from midnight to noon. Statistics show that tornadoes generally will only strike a North American city about every 250 years, with the exception of cities in Oklahoma.
My second article talks more about the general patterns of tornadoes, some factors involved with tornadoes and why the United Stated is hardest hit by tornadoes.
Tornadoes are defined as violent columns of rotating air that are usually visible, but not always. Most tornadoes average 5-7 minutes long and are known to come in contact with the ground. 95% of tornadoes rotate counter clockwise because they move in the same general direction as the low pressure systems that spawn them. As winds get pushed upwards in the "updraft", the prevailing direction rotation is counter clockwise.
Although hundreds of tornadoes affect the entire world, the largest number hit in the mid-west part of the United States, called "Tornado Alley." Some factors in the United States that make it a prime location are local geology, proximity to water and the movement of frontal systems.
Five key reasons that the United States is hit hardest by tornadoes are:
1. Central plains-perfect flat alleyway between the Rockies and the Appalachians creating a straight shot for cold polar air to clash with moist warm air.
2. Other countries are shielded by mountains or geographic boundaries
3. The size of the United States if very large.
4. Ocean front property
5. Ocean currents are aimed at the East Coast.
I live in a town in Northwest Iowa and have fortunately never had to live through a tornado. Many towns that are within 30 miles of my hometown have been hit by tornadoes and extensive damage has impacted and destructed those communities. I know most of these tornadoes hit between noon and sunset which statistics say that 60% of tornadoes do occur during this time. All of these tornadoes included a thunderstorm before, during or after they occurred. Now that I know more about location, frequency and causes of tornadoes, I really don't know as much about the sizes of tornadoes. My next inquiries include:
What is the average size of a tornado?
What does the climate and geographic location have to do with the size of tornadoes?
What regions have been impacted by the largest tornadoes?
Sources:
The Medical Impact of Tornadoes in North America
Jay J. Bohonos (M.D.) /David E. Hogan (D.O.)
2. Weather About.com
Tornadoes-How Tornadoes Form
By Rachelle Oblack
3. Photos:
en.wikipedia.org
blog.al.com
tornatrix.net
johnenglander.net
sodahead.com
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