“RARE FOG” Image On Rannoch Moor In Scotland

A stunning image of a rare fog bow has been captured by a photographer over the snow-covered Scottish moors.

Melvin Nicholson snapped the fog bow on Rannoch Moor whilst out walking on Sunday November 20th.

A fog bow is a colourless rainbow made up of tiny water droplets that cause fog. Due to the small size of the water droplets it has very weak colours, with a red outer edge and bluish inner edge.

Mr Nicholson said: ‘I have never seen a fog bow before and understand that it is very rare.

‘It was an amazing thing to witness and can generally only be seen if the sun is behind you when you are looking at it.

‘As soon as I saw this wonderful isolated windswept tree, I knew that it had to be framed by the fog bow. Freshly fallen snow set the scene all around.

‘It was just beyond magical and one of those days that you’ll remember for a long time to come.

Mr Nicholson is not the only photographer to spot a fog bow while out walking in the Scottish countryside.

In October last year, photographer Richard Toulson was walking his dog Meg when he spotted the strange sight.

The 53-year-old took a picture of the fog bow on his iPhone while on a 10-mile morning hike near Dumfries.

He said: ‘I noticed there was a heavy mist or light fog in the valley at Collochan. Upon going down into the valley I noticed a strange rainbow in the fog.

‘Despite being the same shape as a rainbow it had no other colours than white.

‘It was quite eerie. I’ve never seen one before. It’s one of the regular walking routes we do. It was about halfway through the walk I saw it.’


Fog bows are formed in the same way as rainbows in that light is reflected inside tiny water droplets and emerges to form a large circle or arc of approximately 42°C centred on the opposite the sun.

However, there are major differences. Rainbows are formed by raindrops which are so large that rays passing through them follow well defined ‘geometrical optics’ paths.

With the very finest droplets, such as those forming mist or fog, the light is no longer reflected and refracted within the drops, but is diffracted by them instead to produce a much broader and pale bow – the fogbow. In other words the fog and mist droplets are too small to refract light.

Light hitting the tiny droplets merges into white, rather than being separated into rainbow colours. Fogbow colours are whiteish because the fogbows formed in each colour overlap considerably.

Sometimes the inner and outer edges show faint bluish and reddish tinges. The actual colours are a result of the actual size of the water droplets.

When seen from within cloud or fog, the fogbow may be a partial or full circle. When seen from an aircraft cloud droplets might produce a similar bow. Fogbows are frequently seen over Arctic waters, but are also well known to mountain regions.

The typical colourless fogbow above has been observed by Simon Caldwell (1999) at Glen Lyon in the Grampian Mountains.

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