© Derek RyanA green flash is a phenomenon in which part of the sun can be observed suddenly and briefly changing colour.
But an amateur photographer has managed to record the elusive 'green flash' of the sun, an optical phenomenon that makes the sun appear to turn green as it rises above the horizon.
Derek Ryan, 50, spotted the unusual sight during an early morning walk at the beach at Tarves, Aberdeenshire, before work.
© Derek Ryan
© Derek RyanAn amateur photographer has managed to record the elusive 'green flash' of the sun, an optical phenomenon that makes the sun appear to turn green as it rises above the horizon.
According to Nasa, the almost-mythical spectacle is caused by the atmospheric bending and scattering of sunlight.
Acting like a prism, the atmosphere of the Earth breaks white sunlight into individual colours, bending red colours slightly, and green and blue hues through increasingly larger angles.
It tends to lasts only a second or two during sunrise or sunset - which is why it is referred to as a flash - as the sun changes from red or orange.
A green flash is more likely to be seen in clear air when more of the light from the sun reaches the observer without being scattered.
Mr Ryan, a community nurse from Aberdeenshire, witnessed the spectacle on a local beach on 4 November.
He said: 'It's a phenomenon that you can see every now and then.
'When you know where the sun rises then it can be fairly common to see.
'It was a nice morning and I was walking along the beach before my shift and managed to catch it just at the right time.
A Green Flash captured in time lapse Santa Cruz, California. The phenomenon tends to lasts only a second or two during sunrise or sunset - which is why it is referred to as a flash - as the sun changes from red or orange
'It was stunning. It was the first time I managed to get a good shot of it.'
The flash is so fleeting that many people believe that anyone lucky enough to witness it will always be true 'in matters of the heart.
This image shows the development of a green flash at sunset in San Francisco. The phenomenon appears to show part of the sun suddenly and briefly changing colour
I've tried it time and again, including trying to be tricky and record video in hopes of pulling out a still with the flash - but I never got a picture of it, tho' I've seen it a few (very few) times.