How do tornadoes work?
That is not fully understood and is the topic of ongoing research by scientists. What is known is that tornadoes are violently rotating vorticies of air that form during some thunderstorms. Wind air in and near a tornado spiral inward and upward at very high speeds around a center of intense low pressure.
Most tornadoes form from the mesocyclone, or rotating updraft, of a powerful type of thunderstorm called a supercell. The bottom portion of the mesocyclone tightens and intensifies to produce the tornado, but it is not known how this happens or why happens in some storms and not others.
The number of tornadoes in 1900 is not known. Official records for the United States only go back to 1950, and the vast majority of tornadoes were missed. Work by tornado expert Thomas P. Grazulis indicates that there were at least 51 significant tornadoes (F2 or stronger or causing a death) in the U.S. in 1900. However, most tornadoes are not rated as significant, and many F2 tornadoes may still have been missed.
That is difficult to determine. Records of F1 tornadoes before the 1980s are unreliable as many tornadoes that would likely be rated F1 were missed. The only extensive published work from before 1950 only lists F1 tornadoes if they result in a fatality, and killer F1's are rare. Since 1950 Florida has recorded 846 F1 tornadoes.
How can the work of scientists who want to get close to tornadoes help people who want to take shelter from tornadoes?
Tornadoes are sometimes divided into "weak" tornadoes "strong" and "violent" tornadoes. Weak tornadoes are those rated EF0 and EF1. Most tornadoes are weak. Strong tornadoes are those rated EF2 and EF3. Violent tornadoes are those rated EF4 and EF5. They are the rarest of tornadoes, only about 1% of tornadoes are this strong.
As is typical the greatest number of tornadoes in 200 hit the Great Plains with a large number also occurring in Florida. The top 5 states for tornadoes that year were. Texas with 147 tornadoes. Florida with 77 tornadoes. Colorado with 60 tornadoes. Nebraska, also with 60 tornadoes. Kansas with 59 tornadoes.
Scientists who study tornadoes do various things. Some such as Josh Wurman use a Doppler radar mounted on a truck to gather wind and other data from a distance. Others work on deploying probes, which carry scientific instruments, to take measurements from directly inside a tornado. Still other scientists work on creating computer models of thunderstorms and tornadoes.