Planes May Trigger Snowfall

An image believed to be that of a hole-punch cloud. Scientists say airplanes create these patterns when they fly through certain types of clouds. The water in the clouds can turn to rain or snow and fall to the ground.



All Things Considered: 

The idea for the study came in 2007, when a plane full of weather scientists flew through a very odd snowstorm near Denver International Airport.
The storm was unusual because it produced only a narrow strip of snow leading from the runway, says Andrew Heymsfield, a senior scientist at the National Center for Atmospheric Research and one of the study's authors.
So the scientists did some research on the storm, Heymsfield says. And they found that the narrow band of snow they'd flown through followed the exact flight track of two turboprop aircraft that had taken off a few minutes earlier.
"The quite amazing thing was that their flight track actually produced about an inch of snow at the ground," he says.
The scientists were pretty sure the planes had made that snow fall, Heymsfield says. But they wanted to know precisely how.
They knew that research in the 1980s had found that airplanes, especially those with propellers, could cause ice crystals to form when they flew through certain clouds at just the right temperature.
So it seemed plausible that planes could trigger a little snow. And Heymsfield found evidence that they often did cause precipitation close to their flight path.
But as he used satellites and airport data to study the phenomenon, he realized that a single aircraft could also cause snow to fall for miles around.

That is pretty cool.  Get a bunch of geeks together, and they'll find something to wonder about.  Nothing like a bunch of civil engineers riding a bus, drinking beer and staring out the window at bridges and stuff.  But be careful about hanging out with surveyors, they'll want to retrace the original survey of some Meridian somewhere, possibly in pioneer garb, and everyone knows that pioneer surveyors got awful lonely and cold at night out in the woods with no females around.