Lightning Safety Ask Dave a weather question

Dave Thurlow, Host

 
The average American has seen or heard thousands, if not millions, of advertisements. This gives us all a finely tuned sense of just how excruciatingly long 30 seconds can be. But did you know that same 30-second interval could help save your life? Hi, I'm Dave Thurlow from the Mount Washington Observatory and this is The Weather Notebook.

NOAA Photo

A team of scientists has come up with some new lightning safety guidelines, just in time for the summer of '99. The new guidelines include something called the 30-second rule. It all relates to the speed of sound, which is roughly 700 miles per hour. At that rate, it takes about five seconds for a sound wave like thunder to travel one mile. If you start counting the number of seconds after a lightning flash, and you keep counting until you hear the thunder, you can then divide by five to get the distance to that flash in miles. But how does all this relate to the 30-second rule?

Well, the experts tell us that once lightning has moved to within about five or six miles of your location, at high risk for getting struck. So if you see lightning and then hear thunder within 30 seconds, it's time to get yourself inside. That's the 30 second rule and it just goes to show that ligtning can strike up to 5 or 6 miles away from the storm itself.

Today's contributing writer is Robert Henson. For more information on lightning safety, visit our website at weathernotebook.org. Our show is underwritten by Subaru and the National Science Foundation.