Sunday, July 26, 2009

Noctilucent Clouds

A beautiful display of Noctilucent Clouds last week from my back garden.

Noctilucent Clouds are rare and only happens in certain conditions.

'Noctilucent clouds are the highest clouds in the sky at a height of about 50 miles, which puts them at the top of the mesosphere. These can only be seen during the summer between about 50 and 65 degrees north and south. At any higher latitude it doesn't get sufficiently dark enough to see them.
These clouds look very similar to high cirrus but are bluish or silver in colour and, like the nacreous clouds, are illuminated when the sun is below the horizon, in this case some 6 to 12 degrees.
...most scientists now believe that they are made of water ice.There has been a lot of speculation on what they are made up of and how they are formed, but most scientists now believe that they are made of water ice. But how do these ice particles exist in what should be the warmest part of our atmosphere, and how do they get there in the first place? The answer is probably gravity waves.'

They are certainly wonderful to see from my garden!

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