Two weeks ago, we got drowned here in New York when a flash storm dumped three inches of rain on the city. It doesn't sound like much, but considering that about 13 million gallons of water flood into the subway on a completely bone-dry sunny day, the additional gallons totally b0rked the system -- and the trains ground to a halt, which meant New York ground to a halt.

So I was intrigued to happen upon a recent study claiming that cities actually increase the intensity of storms. Two Princeton engineers gathered a boatload of data about a humongous storm that slammed Baltimore in July 2004, looking at lightning strikes, rainfall, clouds and aerosols. Their conclusion? The structure of the city exacerbated the storm -- producing 30 per cent more rainfall than had the storm passed over a piece of nearby non-urban countryside. As they noted in a press release:

Much of the lightning during the 2004 storm wrapped around the western edges of Baltimore and Washington, D.C., to the south. "It's as if all of a sudden the lightning can 'feel' the city."

Sentient thunderstorms. I love it. Run for your lives!!

Seriously, though, they hypothesize that there's a bouquet of urban-design-related vectors at play here, including the "urban heat island effect", which adds energy to a thunderstorm, as well as tall buildings that increase wind drag and provide "boiling action" that boosts rainfall. Pollution, they think, might also increase the yield.