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On September 17th, 1998 the Ithaca Journal ran its first "Ask A Scientist!" article in which Professor Neil Ashcroft , who was then the director of CCMR, answered the question "What is Jupiter made of?" Since then, we have received over 1,000 questions from students and adults from all over the world. Select questions are answered weekly and published in the Ithaca Journal and on our web site. "Ask A Scientist!" reaches more than 21,000 Central New York residents through the Ithaca Journal and countless others around the world throught the "Ask a Scientist!" web site.

Across disciplines and across the state, from Nobel Prize winning scientist David Lee to notable science education advocate Bill Nye, researchers and scientists have been called on to respond to these questions. For more than seven years, kids - and a few adults - have been submitting their queries to find out the answer to life's everyday questions.

Previous Week's Question Published: 6 January, 2000 Next Week's Question
Intense weather condition, aids creation, formation of tornadoes
Question
Where do tornadoes come from?

Question
Tornadoes are associated with thunderstorms, however, not all thunderstorms will produce tornadoes. Certain weather conditions, which help develop severe thunderstorms, are more conducive to the formation of tornados than others. These weather conditions include strong southwesterly winds around 30,000 feet and strong, southerly, low-level winds around 5,000 to 10,000 feet carrying moisture laden air northward. In addition, the mixing of three different air masses increases the potential for severe thunderstorms and tornado formation. The types of air masses involved are: Continental tropical (cT) which is warm and dry, continental polar (cP) which is cold and dry, and maritime tropical (mT) which is warm and moist.

The United States has the highest occurrence of tornados because all three air masses can be in close proximity to one another. This region is located from Texas through Oklahoma and into Kansas. The cP air mass moves south from Canada, the mT air mass moves northward from the Gulf of Mexico and the cT air mass moves northeastward from northern Mexico.

Since the polar jet stream plays such an important role in the formation of tornados, the tornado season migrates with the polar jet stream. The peak period of April to June for the formation of tornadoes is due to the cT air mass, which forms during the winter months in the desert southwest area of the U.S. and northern Mexico. This air mass is moved northeastward by the polar jet stream during the spring and early summer. You might expect a similar peak in tornado development in the fall as the jet stream moves south for the winter. The reason there is no peak in the fall is the lack of the cT air mass, which has disappeared by July. The formation of tornadoes is complicated and is caused by many factors which we are trying to understand. With the aid of new instruments such as radar, satellites, and faster computers and new ideas, the mysteries of tornado formation will become clearer in the future.

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