This article was originally published by The Conversation. It’s been a warm day, maybe even a little humid, and the tall clouds in the distance remind you of cauliflower. You hear a sharp crack, like the sound of a batter hitting a home run, or a low rumble reminiscent of a truck driving down the highway. A distant thunderstorm, alive with lightning, is making itself known. Every second, lightning in thunderstorms flashes at least 60 times somewhere on the planet, sometimes even near the North Pole. Each giant spark of electricity travels through the atmosphere at about 200,000 miles per hour. It is hotter than the surface of the sun and delivers thousands of times more electricity than the power outlet that charges your smartphone. That’s why lightning is so dangerous. Lightning kills or injures about 250,000 people around the world every year, most frequently in developing countries, where many people work outside without lightning-safe shelters nearby. In the United States, an average of 28 people were killed by lightning every year from 2006 to …