10 September, 2003

Polar Stratospheric Clouds

Tonight we probably had our last display of polar stratospheric clouds, PSCs. The type we see here are called nacreous clouds, a word derived from Mother of Pearl for the beauty of the colors you see.

High up in the sky in a part we call the stratosphere is air that is very dry and cold. Clouds have difficulty forming in this region, but here in Antarctica, we are so cold that the clouds can still form. By chilling the air, molecules slow down until they begin to stick to each other to form a cloud. You see this same thing when you place a cold drink on a table and it gets wet on the outside of the glass. The water in the air chills and forms droplets that stick to the glass. In the stratosphere the molecules chill and form ice crystals. These are mostly crystals of water but they also have crystals of nitric acid in them. These crystals refract sunlight just like a prism or a piece of glass dangling in front of the sun. The colors they produce are simple awesome.

Nacreous clouds have a lot to do with ozone. They provide a place where chlorine atoms can be freed from compounds and then do damage to the ozone. These are the CFCs we talked about earlier that have polluted our atmosphere.

I attach many pictures of nacreous clouds. Enjoy.

Today we had a perfect night launch and I had a chance to drive up to Arrival Heights and Scott Base.

Folks, the data is coming in, our ozone hole is forming rapidly now.

Nacreous clouds.

Nacreous Clouds

Nacreous clouds.

Night over McMurdo. That is the moon and directly above it you may be able to see Mars. In the back is Mt. Erebus.

Nacreous Clouds.