Lucy in the Sky ...

We are already back in Nassau, but a few days ago we saw something rare during a whale watching tour in Tromsø: stratospheric clouds (supposedly of type 2, i.e. water/ice clouds).
They are quite easy to recognize due to their rainbow colors, which brings me to this question: Why are clouds in the stratosphere so colorful but the usual clouds in the troposphere just black and white?
I think I have an answer, but I would prefer to hear an opinion from readers first ...

3 comments:

Anonymous said...

Diffraction from the tiny (10 micron) crystals of water ice and nitric acid. Their size and acid content make them ideal destroyers of ozone.

The tiny size is probably due to the extremely cold temperatures at which they form.

wolfgang said...

>> ideal destroyers of ozone.
what little I know about stratospheric clouds is that type 1 destory the ozon layer, but type 2 is mostly water/ice and does not.

According to our Norwegian guide we saw type 2 clouds, which a trained eye can distinguish I guess.

Anonymous said...

Wikipedia: http://en.wikipedia.org/wiki/Polar_stratospheric_cloud

Complete with the somewhat obscure statement: Only Type II clouds are necessarily nacreous[1] whereas Type I clouds can be iridescent under certain conditions, just as any other cloud.