Noctilucent clouds

Sometimes one can take nice pictures just from the balcony. Yesterday I got a message that rare noctulicent clouds could be seen over the Netherlands. These clouds can only be seen just after sunset of just before sunrise. So I had a look outside and there they were, luminescent clouds against a dark sky.

Noctilucent clouds are very high clouds, ca. 80km above the earths surface (against maximally 20km for normal clouds). Because they are so high, they can reflect the suns light a lot longer even after all other clouds don't receive any sunlight anymore. Three things are needed for noctilucent clouds: dust, e.g. from meteorites, water vapour and low temperatures. Because of the low temperatures, the water vapour forms a thin layer of ice around the dust particles (like frost on earth). This layer of ice now serves as a mirror to reflect the sunlight, and this is the light we see.

Picture is taken from a tripod with a 10 sec shutter speed. Because of the wind, the trees in the foreground are a little blurred. Not my best picture, but I still wanted to share it as I'd never seen this myself before.