Types of PSC
PSCs are classified into three types Ia, Ib and II according to their chemical composition.
- Type I clouds contain nitric acid and water.
- Type Ia clouds consist of crystals formed from nitric acid dihydrate (NAD) or trihydrate (NAT) and water.
- Type Ib clouds droplets additionally contain sulfuric acid and are present in the form of supercooled ternary solution.
- Type Ic clouds consist of metastable water-rich Nitric acid in a solid phase.
- Type II clouds consist of water ice only.
Only Type II clouds are necessarily nacreous whereas Type I clouds can be iridescent under certain conditions, just as any other cloud.
-
A type II (water) PSC showing iridescence
-
A veil of type I PSC, easily confused with cirrostratus clouds or tropospheric haze
-
A type I PSC (white cloud above the orange tropospheric clouds), showing fine horizontal structures in the veil.
Read more about this topic: Polar Stratospheric Cloud
Famous quotes containing the words types of and/or types:
“Our children evaluate themselves based on the opinions we have of them. When we use harsh words, biting comments, and a sarcastic tone of voice, we plant the seeds of self-doubt in their developing minds.... Children who receive a steady diet of these types of messages end up feeling powerless, inadequate, and unimportant. They start to believe that they are bad, and that they can never do enough.”
—Stephanie Martson (20th century)
“As for types like my own, obscurely motivated by the conviction that our existence was worthless if we didn’t make a turning point of it, we were assigned to the humanities, to poetry, philosophy, painting—the nursery games of humankind, which had to be left behind when the age of science began. The humanities would be called upon to choose a wallpaper for the crypt, as the end drew near.”
—Saul Bellow (b. 1915)