Normal tornadoes, just two of them. (Photo: NOAA)

In Oklahoma, one of eight tornados that touched down this week was rotating the wrong direction.

Normally, in the northern hemisphere, tornadoes rotate in a counter-clockwise direction; this one was an “anticyclonic” tornado that was moving clockwise. It traveled thirteen miles, with winds up to 110 mph.

No one knows exactly why some tornadoes decide to stand out by rotating the opposite direction from their brethren. Often, they seem to be satellite tornados, and this one could have fit that model. Another, stronger hurricane was twisting nearby, kicking up enough stormy weather that the anticyclonic tornado was hard to see with the eye. (Radars picked it up, though.)

Tornadoes that rotate clockwise are rare; they were first caught on film in the 1970s. But they can be spectacular—this photo of an anticyclonic storm won National Geographic’s photography context last year.

An anti-cyclonic tornado in Colorado. (Photo: James Smart)

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