Good Question: Why Does Thunder Crack, Roll?

MINNEAPOLIS (WCCO) -- We've all been through it before: you see the lightning bolt, and, seconds later, you hear the boom.

"Lightning causes thunder," said WCCO-TV meteorologist Mike Augustyniak. "And lightning, you can think of as an explosion, because that's literally what it is."

We asked Augustyniak to shed some light on the lightning and thunder question.

He said that when lightning travels through a column of air, it heats to a temperature that is three to five times hotter than the surface of the sun. And it takes mere milliseconds for this to happen.

"Any time you have something heating that quickly, the air is going to expand just as quickly; and that air expanding sends out the shockwave that we hear as thunder," Augustyniak said.

But there are different types of thunder: the shotgun bang, the crack, the roll.

"A lot of different stuff changes the sound," Augustyniak said. "Its shape, how long the lightning bolt is, and also how the atmosphere is set up overhead."

Lightning that travels between clouds tends to make more of a rolling sound. The kind that hits the ground tends to make more of a cracking sound.

It is possible to track how far away lightning is. The seconds between the bolt and the boom is all you need to know.

"For every five seconds you count, the lightning bolt is about a mile away from you," Augustyniak said.

You've likely heard many kinds of thunder this spring, and that's because we have had more storms than usual in the past 30 days.

Thunder can also happen in the winter, but Augustyniak said it's rare, because there isn't the moisture in the atmosphere that there is during the spring and summer.