- A police helicopter captured a stunning photo of a rare full circle rainbow
- To see one, you need to be able to see water droplets below your horizon
They’re often seen as lucky – but try to find the end of the rainbow in this incredible image and you might struggle.
A police helicopter has captured a stunning photo of a rare full circle rainbow over the Vale of Glamorgan in South Wales.
The St Athan-based National Police Air Service (NPAS) South West & Wales Region unit captured the photo after assisting South Wales Police.
‘Afternoon all. A great photo taken from ^DJ earlier today after assisting @swpolice,’ it tweeted.
Here’s what a full circle rainbow is and how it forms.
They’re often seen as lucky, but try to find the end of the rainbow in this incredible image and you might struggle
A police helicopter has captured a stunning photo of a rare full circle rainbow over the Vale of Glamorgan in South Wales
How do rainbows form?
A rainbow is a multicolored arc made by light striking water droplets.
Light entering a water droplet is refracted, and its direction is changed.
Then that light reflected off the back of the droplet.
As this reflected light leaves the droplet, it is refracted again, at multiple angles.
Visible light is comprised of light with many different wavelengths – red has the longest and violet the shortest.
Light of each wavelength is reflected at a different angle and the spectrum is separated, producing a rainbow.
The key factor that determines how much of a rainbow you see is your visual reference point, according to the Met Office.
‘In most cases we only see less than half of a circle – the characteristic rainbow arc we are all familiar with,’ it explains.
‘However, if you are lucky enough to be in the right position at the right time, you can see a full circle rainbow in all its splendour.’
The centre of a rainbow is directly opposite the position of the sun in the sky, which means more of a rainbow can be seen as the sun approaches the horizon.
For this reason, you’ll normally see the biggest rainbows around sunrise or sunset.
However, to be able to see a full circle rianbow, you need to be able to see water droplets below your observable horizon.
‘If you are on the ground you are very unlikely to be in the optimum position to see the rest of the rainbow – except for full circle rainbows that appear in, for example, the mist given off by a garden hose or sprinkler,’ the Met Office said.
‘However, if you are standing on top of a tall building or looking out of an aircraft then you may have water droplets and sunlight below your observation point.
To be able to see a full circle rianbow, you need to be able to see water droplets below your observable horizon
‘If conditions are exactly right, that gives you the opportunity to see the rainbow in its entirety.’
This isn’t the only unusual rainbow spotted recently.
Last year, NASA shared a stunning photo of an inverted rainbow, or ‘circumzenithal arc’, that appeared over a palm tree in Ragusa, Sicily last month.
The rainbow was spotted by Italian astrophotographer and primary school teacher, Marcella Giulia Pace, 47, when the sun was low in the sky.
She captioned her photo: ‘Countless times it will have appeared over our heads and been ignored because everything we need is often in front of us or, with our heads bowed, on our mobile devices.
‘Many define the Circumzenital Arch as “the smiling rainbow”, because its colors are inverted compared to the more common rainbow we observe.
‘Of all the halo phenomena, it is the one with the most vivid and bright colors, as seen in the photo, even more vivid than those of the rainbow.’