Did you see this mysterious vapour trail or cloud over King's Lynn yesterday?
At first, it looked like an aircraft had performed a U-turn over South Wootton around 4.30pm.
Except the radius of the turn was so tight it seems unlikely a plane could have performed it.
Could it perhaps have been a rare horseshoe vortex cloud?
The Cloud Appreciation Society's website says: 'This cloud forms in a region of rotating air, or vortex. Such vortices usually form vertically, sometimes leading to waterspouts or even tornados, but occasionally they can develop with a horizontal axis and give rise to a gently rotating crescent of cloud.'
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