by Curt Kovener 
Whether it is a dark cloud on the horizon or one with a silver lining or one in the shape of a rabbit or your late Uncle Chester’s uniquely large nose, or a cloud where current technology saves your computer files (which isn’t the kind of clouds we are discussing this week) there are scientific minutia about clouds that you probably didn’t know.
First the basics: When moist, warm air rises to a cooler elevation, water condenses onto microscopic “seeds” like dust, ash, or bacteria. Water + seeds + updraft = clouds.
If there’s more water vapor than places for it to condense, already-formed ice crystals can also serve as seeds. As the crystals take on moisture, they may become too heavy for updrafts to support. When that happens it is time for the umbrella.
Nacreous clouds, or “mother of pearl” clouds, appear iridescent because of their ultrafine ice crystals, which form 10 to 15 miles up in the stratosphere. Unfortunately, the pretty nacreous clouds also support chemical reactions that convert benign chlorine-containing molecules into a form that destroys Earth’s ozone layer.
Roll clouds form when updrafts and downdrafts churn clouds into a long, spinning cylinder. They look spectacular, but they often herald an approaching storm front.
Even higher: 50 miles up, noctilucent, or “night shining,” clouds glow an eerie bluish white. They are invisible by day, but after sunset they catch solar rays shining from far below the horizon.
A June 2010 hailstorm in South Dakota dropped the largest hailstones in U.S. history. They were nearly as large as a soccer ball and weighed two pounds.
And you should know that pollution equals big time damage. An Israeli-American team correlated 15 years of pollution records with the National Weather Service Storm Prediction Center’s records on storms. They found that hailstorms over the eastern United States peak in the middle of the week, when summertime air pollution is at its worst.
Cumulonimbus clouds are the ones that make your airline flight late. Their winds are so intense and unpredictable that pilots never go through them…but sometimes over them and the ensuing storm.
That the winds in a cumulonimbus are so intense were borne out in 1959 when Lt. Col. William Rankin was flying his F-8 fighter jet over a cumulonimbus when the aircraft’s engine failed. He parachuted out and spent the next 30 minutes bounced around inside the storm. Amazingly, he survived.
And if that didn’t cloud your thinking, in 2007 German paragliding champion Ewa Wisnierska experienced “cloud suck.” While gliding under a cumulonimbus, she was pulled upward to 32,000 feet. She blacked out due to lack of oxygen but regained consciousness at roughly 23,000 feet.
So if the weather prognosticator warns of impending storms, keep an eye out for those dark clouds rolling in.
And take cover.
