They are classified as being between F-O and F-5 in strength. F5 tornadoes can be a mile and a half wide and have speed over 260 miles per hour. Since you can’t measure the speed of a tornado, people look at the damage they have done to figure out how strong they were. My papa built a website for a customer who sells tornado shelters, so he is helping me with this post. You can look at that website by clicking HERE.
Above are some really cool pictures: