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Dave Thurlow, Host

 
It's summer, it's hot and humid, afternoon storms are brewing. You may not know it but you're surrounded by sferics. S-f-e-r-i-c-s. Hi, I'm Dave Thurlow from the Mount Washington Observatory and this is The Weather Notebook.

Lightning storm over Boston 1967 - NOAA Photo Collection

What the heck are sferics? Can you see 'em? No. Can you hear 'em? Well, sort of. Sferics create the noise called static that you can hear on AM radio. Like this (sferic sound). Now wouldn't it be funny if while listening to our recording of sferics you actually heard real sferics on your AM radio. Hey Bryan how many AM stations are we one?

Bryan: "Um nine."

Well, it could happen.

Even if you're listening to FM you might someday have a reason to check out AM. That reason could be to check your local area for thunderstorms. For it is lightning that creates sferics.

Sferics are simply the radio waves produced by the current-carrying lightning channel. The further the lightning flash is from you and your radio, the fainter the crackle (sferic sound). The closer the flash, the louder the crackle (louder sferic sound). For this reason, your AM radio acts as an effective lightning detector, warning you of approaching thunderstorm activity.

So, the next time you're listening to AM radio and you hear sferics, be sure to take shelter, because soon enough, you could here this (sound of lightning).

For more information on sferics, or on just about anything we've ever covered here at The weather Notebook, be sure to visit our website at mountwashington.org. Which is of course static free.

The Weather Notebook receives major support from the National Science foundation, and is underwritten by Subaru, the beauty of all wheel drive.