Noctilucent Clouds - June 2005


On a couple of nights around midsummer, noctilucent clouds put in an appearance from southern England. The display of 19th June was the best I had ever seen, and the first I have photographed.

It was quite by chance that I happened to be outside putting the rubbish out for collection and noticed a strange metallic blue light in the northern sky. Normally you would expect the orange glow from the lights of London in this direction, but this was entirely different! After a few moments for my eyes to adapt to the dark I recognised this as noctilucent clouds - the first I have seen from this far south. I rushed indoors and in a few minutes had a camera rigged up on its tripod to catch the scene...

The pale blue clouds peek out above the trees in this view north from Hurst Green. The ridge upon which the trees stands unfortunately blocks the view to the horizon and so obscures a good proportion of the clouds. It was too late to move to another location with a better view - as the Sun got lower below the horizon so the clouds would disappear from view, but I wasn't sure when this would be.

The sky was beautifully clear, and with no hint of the orange glow from the lights of London, whose centre is some 22 miles (35km) away in the direction in which this picture was taken. The noctilucent clouds themselves, at an altitude of around 50 miles (80km) are too high to be affected by light pollution and are also much further away than London. Taking an altitude of 50 miles and an elevation of 20 degrees, some simple trigonometry reveals that the clouds must be at least 138 miles (220km) away.

The clouds are not just a uniform glow but contain a delicate structure, as this close up photo reveals...

Some, though not all, of the noctilucent clouds show a fine criss-cross structure.

Two stars are visible in the picture - near the centre is Menkarline (Beta Auriga) and at the right is Capella, the brightest star in the constellation of Auriga.

The following two nights were cloudy so it was not until 22nd June I was able to see the clouds again. This time they were much reduced, and had I not positioned myself on a good spot on the North Downs, with a clear view to the horizon I would not have seen them.

These wavy blue blue noctilucent clouds are quite distinct from the much lower, but also wispy, cirrus clouds, which show up dark against them. The cirrus clouds are also lit orange by the light pollution from London, which does not affect the noctilucent clouds, which are lit by sunlight coming up from beyond the northern horizon.

This view is almost exactly due north and the towers of London's Canary Wharf financial centre illuminate the skyline despite being nearly 20 miles (32km) away.

The bright star to the left of this picture is Capella. Given that the noctilucent clouds do not reach it you can see that this display was much reduced compared to that of 3 days earlier. Conversely, if I had been at this spot 3 days ago then I would have seen the noctilucent display in all its glory.


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