Saturday, August 3, 2013
The Best Video of the May 20 Moore Tornado I've Seen
Because the photographer is behind the tornado he has a clear view. Behind the tornado the air sinks which clears out some of the humidity and gunk (official meteorological term).
One comment: You cannot determine the intensity or F-scale value from looking at the storm. That said, damage like this would clearly indicate it is a major tornado as electrical transmission towers are engineered to withstand substantial wind loads.