Moonbow lights up our skies

Thursday 25 August 2016

Red sky at night is said to be shepherd's delight but it was a rare moonbow that impressed Islanders out west last night.

The big rainbow produced by moonlight rather than sunlight was caught on camera by a number of Islanders including Rob Hansen who sent us this great shot he got while out walking his dogs in St Mary.

The lunar rainbows are rare natural atmospheric phenomena that occur when the Moon's light is reflected and refracted off water droplets in the air. They are much less common than rainbows and are fainter so are much more difficult to see.

However an alternative theory is that the sun caused the rainbow from below the surface horizon.

Jersey Met's Principal Meteorological Officer John Searson said: "The Sun set at 20:07 last night so the Sun had set 14 minutes before the picture was posted. It is likely that the rain falling from the cloud (Altocumulus Castellans) at 14000ft still had sun shining directly on it and acted like a prism in the normal way. 

"Because much of the light from the sun has been removed as it passed through the atmosphere (the reason why the sun sometimes turns red towards sunset, the colour is not the normal rainbow colour.

"I've never seen a rainbow after sunset, but I will look out for them in future."

Here's an image from Jersey Met showing the rainfall that fell five minutes before Rob's picture was posted on Facebook.