BOLTS AND BLAZES

Earlier this month an estimated 11,000 lightning strikes in California ignited about 370 known fires, with 23 becoming major fires. Two of the fires still burning are some of the biggest in state history. Here’s a look at lightning and California’s biggest burns.

LIGHTNING LESSONS IN A FLASH

Your odds of getting struck by lightning this year are about 1 in 1.2 million, but the odds of it starting a devastating fire in California are much higher. There are in-cloud lightning, cloud-to-cloud lightning and cloud-to-ground lightning. Several reports cited the fires in August were caused by heat lightning. But according to the National Weather Service, heat lightning is any lightning or lightning-induced illumination that is too far away for the thunder to be heard. It may have reddish color, like sunsets, because of scattering of blue light. Spider lightning refers to long, horizontally traveling flashes often seen on the underside of stratiform clouds. The map below is a NASA satellite-generated map that shows where lightning is most common on Earth. The dark red areas are where it is most intense. The state of California is not dark red. Over the contiguous 48 states, an average of 20 million cloud-to-ground flashes have been detected every year since the lightning detection network covered all of the continental U.S. in 1989. The National Severe Storms Laboratory gives a simple explanation of lightning as a giant spark of electricity in the atmosphere among clouds, the air or the ground. In the early stages of development, air acts as an insulator between the positive and negative charges in the cloud and between the cloud and the ground. Lightning causes thunder. Energy from a lightning channel heats the air briefly to around 50,000 degrees Fahrenheit, much hotter than the surface of the sun. This causes the air to explode outward. Light travels at a constant 186,000 miles/second, while sound travels at about 760 miles per hour. The National Weather Service says if you count the number of seconds between the flash of lightning and the sound of thunder, and then divide by 5, you’ll get the distance in miles to the lightning. So five seconds is equal to 1 mile, 15 seconds is equal to 3 miles. Thunder can be heard from up to 25 miles away. A “bolt from the blue” is a cloud-to-ground flash that typically comes out of the side of the thunderstorm cloud, travels a relatively large distance in clear air away from the storm cloud and then angles down and strikes the ground. A helmeted bicyclist experienced a lightning strike to the head under fair weather conditions with a cloudless sky. It was determined that the bolt probably originated in a thunderstorm that was about 10 miles away. Lightning can have 100 million to 1 billion volts, and contains billions of watts. Lightning can strike from the sky down or from the ground up.