Don’t mess with lightning. Period. All the experts, people much smarter than me, say that when a storm approaches and you hear thunder, stop your outdoor activities immediately and seek shelter in a building or a car. Stay there until the storm passes.

There’s a lot of lightning in Arizona and much of it comes during the monsoon. On average, the state sees more than ½ a million lightning strikes, lightning that strikes the ground, and probably more than 2 million total flashes when you count lightning within clouds.

Which brings up the interesting question. Is it really cloud-to-ground or the other way around? Or a little bit of both?

A little of both, it turns out.

[SPECIAL SECTION: Arizona Monsoon 2017]

Most lightning that strikes the ground is negatively charged. It starts with an invisible “stepped leader” from the cloud. As it nears the ground, it’s met by a “streamer” which is a positive charge reaching up. When they meet, a “return stroke” of bright light travels back to the cloud at more than 50,000 miles a second. That’s the first part we usually see. Lightning can flicker along essentially the same channel more than a dozen times.

Positive lightning works the same way, just reversed, with a positive leader from the top of the thunderstorm meeting an uprising negative streamer to make the electric connection. Positive lightning can be 10 times more powerful than negative lightning and strike farther from a storm. It also does more damage and, probably, is responsible for most of the lightning-caused wildfires.

We’ll talk about sprites later this summer. And bipolar lightning. Yeah, it’s a real thing. In the meantime, stay safe when thunderstorms form and lightning develops.

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Copyright 2017 KPHO/KTVK (KPHO Broadcasting Corporation). All rights reserved.

Arizona’s Family Chief Meteorologist | Arizona’s Weather Authority

With 25 years of experience forecasting weather and his vast knowledge of Arizona and its micro climates, Royal is an Arizona Weather Authority.

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