Arizona Lightning by Royal Norman

Lightning near Tucson. (Source: Lori Grace Bailey Photography)
Lightning near Tucson. (Source: Lori Grace Bailey Photography)(Lori Grace Bailey Photography)

PHOENIX (3TV/CBS 5) - 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 half a million lightning strikes 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.

Positive streamers reach up to meet stepped leader (Source: Mike Olbinski Photography)
Positive streamers reach up to meet stepped leader (Source: Mike Olbinski Photography)(Mike Olbinski Photography)

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 (Source: Karen Swanson Photography)
Positive Lightning (Source: Karen Swanson Photography)(Karen Swanson Photography)

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.

Another type of lightning that’s called sprite lightning actually occurs high above the the storm clouds.

Sprite Lightning (Source: Ben Cherry Photography)
Sprite Lightning (Source: Ben Cherry Photography)(Ben Cherry Photography)