Typically, the Enhanced Fujita Scale is a rating (scale – EF-scale) on how powerful a Tornado was once it has struck.
The rating of a Tornado is calculated by surveying the damage and comparing it with damage to similar objects at the same sort of wind speeds.
It has been suggested that this particular rating scale is not meant to be used as a measure of how strong a Tornado is currently on the ground is.
The EF-scale is divided into six categories: EF-0, EF-1, EF-2, EF-3, EF-4 and EF-5. The image below illustrates the EF-scale brilliantly .
To find out more about the EF-scale, visit https://www.spc.noaa.gov/efscale/