One of the biggest risks in the wilderness in the summer is one of nature’s coolest phenomenon: Lightning! I was super terrified of lightning when I was little, until I turned 4 and my dad put me on his shoulders one day and made me hang out in the garage to watch it. Now I think it’s the coolest! One of the keys to being safe on a mountain in a thunderstorm is to know how lightning works. If you know how lightning works, you know how to avoid it!

Lightning 101:

When it gets all hot and sticky outside, water evaporates and heads up into the atmosphere as water vapor. When these excited, vapor molecules jitter their way high enough in the atmosphere, it gets cold and they start to turn back to droplets and ice, which is what creates those big ol’ thunderheads. The freezing molecules fall back towards the earth, rudely smacking into the other rising molecules on the way down. Combined with some strong wind action, these water molecules have their own little demolition derby and electrons fall off the molecules they were riding. These ride-less electrons sink low in a cloud and the rest of the water molecule rises to the top of the cloud. An electric charge starts to form, with the top of the cloud being positive and the bottom of the cloud being negative. It’s kind of like those battery and light bulb experiments you did in 8th grade. All it needs is a wire, or conductor, to close the circuit. The electric fields become so strong, they actually repel electrons into the surface of the earth, and create a positive electric field on the surface of the earth.¹

Now, like two lovers in a slow-mo running scene in a meadow, reaching out for each other, the cloud starts to send down streamers of ionized air called step leaders and the earth sends up positively charged streamers. When the air is ionized, it conducts electricity like a metal rod.¹   If you are outside in a storm and your hair starts to stand up, those are the positively charged streamers, cruising through your body and reaching for the sky.² It’s a sign that a lightning strike is imminent! As these two opposites-attract, beach-running lovers meet, the circuit is closed and ZAP, the electricity flows! The flash of light along the step ladder is actually super-heated, exploding air, caused by the sheer amount of current. Thunder follows, caused by the shockwave of the air molecules exploding.

This is a really cool video on how step leaders work:

So that’s the origin of lightning. A negative charge in the cloud is drunkenly reaching for the positive charge of the earth (or the top of another cloud). The earth reaches back, they connect, and then fireworks!

So how does this help us avoid lightning?

Well first off – plan effectively and be off any above-tree line terrain before noon if there’s a chance of storms in the forecast, as most storms begin to build in the afternoon, as the atmosphere heats up and that water vapor has time to build. If you are above tree line and you see tall clouds forming, or you hear thunder – time to head down! Lightning can strike up to 10 miles from a storm.² A friend of mine from my USFS days, we’ll call him “C,” was climbing with some folks when an afternoon storm rolled in. They didn’t clear out and he was struck by lightning. Luckily, C was ok and they started hiking down the hill. He actually was struck a SECOND time on the way down. Maybe that explains a few of his quirks? So if you hear thunder above tree line, just turn around and get down!

Are you safe in the trees? Well… they are better than being the tallest thing around. Those tall objects have the strongest positive attraction. Generally, trees are taller than you! That said, lightning can still strike that tree you are standing next to, or the ground NEXT to a tall object. Because multiple sources on the ground can send up those positive streamers, lightning can leap around and connect with multiple targets. If you are in the middle of a field, standing next to a lone tree, you are more likely to be hit than if you get out in the field alone. If you are in dense forest? Try to give yourself whatever distance you can from the trees and hang out near shorter trees if possible.

Now obviously, if you are out hiking or backpacking, you aren’t gonna be able to get 100% out of harm’s way. So what now? Find the lowest spot on the terrain you can safely reach. A dip between two hills, or a ravine are great options. Crouch into a ball and try to only have your feet in contact with the ground, ass to ankles style. That makes you a much smaller target and a presents a shorter circuit for the lightning to travel through. If you have a Thermarest or insulated pad while you are backpacking, sit on it, again curled up in a ball. That will help insulate you from any charges travelling through the ground if there is a strike near you. Don’t lay down! You are just asking lightning to channel through your entire body if you lay down. It’s tempting, but don’t snuggle with your buddy for comfort either. Spread out, so that if one person gets hit, the charge won’t arc to your friend’s positive streamers.

The ideal place to ride out a storm is in a building or in your car. Electrical current is channeled through the outside of a building or vehicle and safely connects to the ground, without zapping you. When I worked for the Forest Service, I filled in for a fire lookout on Jumbo Mountain my first summer. They keep these tiny stools, only about a square foot, with rubber bottoms in the lookouts. The idea is that you hop up on that thing during a storm, so the electricity will pass around the outside of the lookout and NOT through you. Imagine being at the peak of a mountain in the midst of a raging electrical storm, the lookout swaying in the winds. Now imagine having to hop on a stool and crouch there for an hour, when all you really want to do is hide in your sleeping bag! Brian stood through a storm this way once and said it was a pretty wild experience!

Lightning striking people doesn’t happen very frequently, but there are about 500 people struck a year in the US alone.² This time of year, in particular, the atmosphere is very unsettled and afternoon thunderstorms are very common. Do the smart thing when you are out in the woods and you won’t practice being a human light bulb!

1. Zavisa, John.  “How Lightning Works”  01 April 2000.  HowStuffWorks.com. <http://science.howstuffworks.com/nature/natural-disasters/lightning.htm>  19 June 2015.
2. Weather Underground. “About Lightning” Weather Underground.com <http://www.wunderground.com/resources/education/lightning.asp?MR=1> 19 June 2015