Land nearby is an MoD testing range where heavy weapons are trialled and soldiers regularly train.
The cloud’s location has lead some conspiracy theorists to speculate it could the aftermath of a rocket launch.
The MoD’s Defence Infrastructure Organisation, which operates the plains is reportedly not aware of any military training which could have caused it.
Calls to the University of Bristol and Somerset Drone experts Atticus have been made, but no one is any wiser as to what exactly it was.
Mr Hargrave said he had never seen anything like it.
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Article source: https://www.express.co.uk/news/science/1085812/mysterious-cloud-strange-spiral-baffling-experts-pictures