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.
(SUN PHOTO/Karl Merton Ferron, 2004)