Pretty white rainbows
- Published
Every now and then we are dazzled by a white rainbow, otherwise known as a fogbow. Imagine our excitement when over the last few days Weather Watchers have photographed three!
A coloured rainbow is produced through refraction where the rays of light in a raindrop are separated out into colours.
However, fogbows form from sunlight interacting with water droplets contained in fog, mist, or cloud, and these water droplets that make up fog are so tiny compared to raindrops that the process of diffraction of the light by the droplet becomes a dominant effect.
The process of diffraction broadens the reflected beam of light which smears out the colours to give the characteristic ghostly white or very faintly coloured fogbow. This also makes the fogbow much broader than a regular rainbow.
Weather Watcher Frances says, "I was staying overnight in Oban [Argyll and Bute] on the way to Mull. On Sunday morning I noticed it was very misty over the sea so I went out to take a picture. By the time I got there the 'fogbow' had started to appear." Photo taken on 1 July
Ron captured this fogbow "on an early morning walk at Green Houses near Lealholm on the North York Moors" on 29 June
Thanks to Violaman for spotting this white rainbow at Druridge Bay, Northumberland, on 1 July