Subtitles section Play video Print subtitles Contrary to popular belief, lightning strikes aren't always a death sentence. In fact, about 90% of people in the US who are struck actually survive. Still, victims rarely walk away unscathed, and the damage can be permanent. Lightning triggers 75,000 forest fires in the US each year, and can split entire trees down the middle in a split second. So, it's frightening to imagine what it does inside a human body. The good news is that you won't get cooked Wile E. Coyote-style, but it can still do damage. For starters, lightning carries between one to ten billion joules of energy, enough to power a 100-watt bulb for at least three months. When that amount of electricity enters your body, it short circuits the small electrical signals that run your heart, lungs, and nervous system. This can lead to cardiac arrest, seizures, brain injury, spinal cord damage, and even amnesia. But electricity isn't your only problem. Lightning is blisteringly hot. In under a second, it can heat the surrounding air to temperatures five times hotter than the sun's surface. This causes a rapid expansion of air, which leads to a shockwave that we hear as thunder. It has been calculated that someone standing within 30 feet of a lightning strike point can experience a blast wave equivalent to a five-kilogram TNT bomb. The intense heat, light, and electricity can also damage your eyes. In fact, it can bore holes in your retina and cause cataracts within days or weeks. Other side effects of lightning can include impotence in men and overall decreased libido. That's just what happens on the inside. As the lightning moves toward the surface, it can force red blood cells out of your capillaries into your epidermis like a bruise. These intricate designs are called "Lichtenberg figures". These intense temperatures can also heat up any metal you might be wearing, causing third-degree burns, and can also rapidly vaporize the rain water or sweat on your skin. The resulting steam explosion may blow off your clothes and shoes, leaving you nearly naked. On average, 47 people in the US are killed by lightning each year. So, you might be wondering, how do I make sure I'm not that guy? For starters, check weather forecast ahead of time and stay indoors during a storm. But if you're stuck outside, avoid isolated trees, poles, and open fields, and run as fast as you can toward safety. You're best off in a developed building or a hard-topped metal vehicle. So, stay calm and just remember: When thunder roars, go indoors.