What does e or f mean in a tornado?

Answer 1

There are three commonly used scales for rating the intensity of tornadoes; the Fujita (F) scale, the TORRO (T) scale, and the Enhanced Fujita (EF) scale.

The Fujita or F scale, created in 1971, was the first scale of rating tornadoes to be developed and is the most well known. It uses the severity of damage caused by a tornado to assign it a rating, ranging from F0 at the weakest with relatively minor damage, to F5 at the strongest, with utter devastation.

The Enhanced Fujita or EF scale replaced the original Fujita scale in the United States in 2007. It similar to the original scale, running from EF0 to EF5, but has more accurate wind speed estimates for each level and uses more detailed damage analysis. As of 2015 this scale is only used in the United States and Canada.