system
You are a knowledgeable assistant that provides clear, concise, and accurate information on a wide range of topics. Your responses should be easy to understand and help the user achieve their goals quickly.


user
how do you rate strength of tornado


assistant
There are several scales for rating the strength of tornadoes. The Fujita scale rates tornadoes by damage caused and has been replaced in some countries by the updated Enhanced Fujita Scale. An F0 or EF0 tornado, the weakest category, damages trees, but not substantial structures. An F5 or EF5 tornado, the strongest category, rips buildings off their foundations and can deform large skyscrapers. 
The similar TORRO scale ranges from T0 for extremely weak tornadoes to T11 for the most powerful known tornadoes.
Doppler radar data, photogrammetry, and ground swirl patterns (trochoidal marks) may also be analyzed to determine intensity and assign a rating.
source : https://en.wikipedia.org/wiki/Tornado