A rare phenomenon that caused a fluorescent cloud in the sky over Bermuda sparked speculation after photographs of the event were shared on social media.

Mark Guishard, the director of the Bermuda Weather Service, said the unusual cloud was caused by a trick of the light known as irisation or iridescence.

Dr Guishard explained: “It is due to the sun's angle against the type of clouds on that day — which appears to be cirrocumulus.

“For the phenomenon to appear, it needs some specific conditions — the right cloud type, at the right height, at the right time of day with no other interfering clouds in the way.”

Dr Guishard said: “The combination of these conditions is relatively infrequent, so it could be considered rare to see in Bermuda.”