Why there's more rain, lightning, on weekdays
Scientists at the Goddard Space Flight Center in Greenbelt have been thinking hard about why rainfall and lightning activity in the Southeastern United States tend to peak on weekdays - 
particularly between Tuesday and Friday.
Their conclusion is that air pollution is likely to blame. And their chief suspects are particulate emissions of the sort spewed by diesel engines.
Their thinking - not yet fully borne out by their research - is that it's the fine particles in the soot, largely from trucks, that provide growing thunderstorms with more surfaces on which water vapor can condense into droplets. More, smaller droplets allow the thunderstorms to grow higher in the atmosphere. The droplets get colder, release more latent heat before they fall, and help fuel more energetic electrical storms.
The data showing there is more rain and more lightning on weekdays, on average, would seem to fit nicely with the fact that more trucks are on the road from Tuesday through Thursday.
You can read more about their work here, on NASA's very interesting "What on Earth" blog.
(SUN PHOTO/Karl Merton Ferron, 2004)
Comments
Aren't those people in the picture doing something dangerous? That is, they are sitting outside, possibly on metal benches, under trees watching lightning happening in their vicinity. I think the National Weather Service says something like if you can hear the thunder, you're close enough to get struck by the lightning.
FR: I'd have to say yes, although I admit I've stood outside admiring lightning displays many times myself. We also play the odds every time we get in our cars, eat oysters or shovel snow. I've done all those things in the last couple of weeks, too.
Posted by: LC | February 22, 2010 9:28 PM
Just to be clear, being in a car is a very safe place to be when there is lightning. Actually driving on roads would be where you would be "playing the odds".
Posted by: Perry | February 23, 2010 2:47 PM