NLC whats the dealeo???

[mark993]

This might sound like a really stupid question, but that has never stopped me in the past

I feel I must be missing the point with these NLCs can anyone explain why so many people are taking pics of them. The pics are nice and all but are they 'special' clouds.

[FraserClarke]

They're very high clouds, so relatively rare (though apparently becoming more common) -- and you can see them at night, which is quite cool, no? Proves the Earth is a sphere

[AndyUK]

In essence, yes....

Virtually all of our "normal" clouds are in the Troposphere (up to c. 15,000m)...

Above this you then have the Stratosphere which rarely has any clouds at all (it's apparently quite dry), but sometimes (if you're lucky) you can sometimes see Stratospheric (Nacreous) clouds (Polar stratospheric cloud - Wikipedia, the free encyclopedia)

NLC's occur in the Mesosphere - They're similar to Nacreous clouds but are the highest clouds in our atmosphere (Noctilucent cloud - Wikipedia, the free encyclopedia)

The lower clouds are obviously mostly made of water particles, but the Stratospheric and NLC's are mostly made of ice particles - The reason they seem to "glow" is that you only see them after sunset or before dawn as the sun lights them from below the horizon (ie from underneath)