Lightning hits the United States about 25 million times a year and kills around 20 people, according to the National Weather Service, with hundreds more badly injured. MinuteEarth's short animation "How to Survive a Lightning Strike" explains in two minutes what happens when a bolt reaches the ground, and the official advice behind it is simple enough to remember on any hike, ski tour or day at the lake.
The MinuteEarth lightning video
MinuteEarth is the science channel started in 2011 by Henry Reich, the creator of MinutePhysics, together with his father Peter and brother Alex. Its hand-drawn style suits lightning well: the danger is invisible current moving through air, ground and bodies, and a sketch can show the paths a photograph never could.
Five ways lightning strikes people
A direct hit is only one of the ways lightning injures people. The National Weather Service describes five:
- Direct strike. The person becomes part of the main lightning channel. It is less common than the others but often the deadliest.
- Side flash. Lightning hits a taller object nearby, often the tree someone sheltered under, and part of the current jumps through the person.
- Ground current. Energy spreads outward through the ground from the strike point. It causes the most lightning deaths and injuries, and kills many farm animals.
- Conduction. Current travels along wires, plumbing and metal fences. Most indoor injuries happen this way, through corded phones, taps and sockets.
- Streamers. Upward discharges rise from the ground as the main bolt approaches, and people caught in one can be hurt even when the bolt lands elsewhere.
When thunder roars, go indoors
The NWS slogan sums up the whole strategy. If you can hear thunder, you are close enough to be struck, so move to shelter straight away. The CDC notes that lightning can strike more than 10 miles (16 km) from the storm, which is why a strike can arrive under blue sky. Stay inside for at least 30 minutes after the last rumble.
Safe shelter means one of two things:
- a substantial building with electricity or plumbing
- an enclosed, metal-topped vehicle with the windows closed
Picnic shelters, tents, porches and isolated trees offer no protection. Indoors, stay off corded phones and wired electronics, keep away from sinks, baths and taps, stay clear of windows and doors, and avoid lying on concrete floors or leaning on concrete walls.
Lightning safety in the mountains
Hikers, climbers and summer skiers are often far from a building when a storm builds. Plan the day so you are off exposed ground before afternoon thunderstorms typically develop, and watch for towering clouds. If you are caught out, the NWS advice is clear:
- get off peaks, ridges and hilltops at once
- never lie flat on the ground
- never shelter under an isolated tree or a cliff or rocky overhang
- get out of and away from lakes, ponds and other water
- keep away from wire fences, power lines and other metal that conducts electricity
First aid after a lightning strike
Lightning victims carry no electrical charge, so you can touch and help them immediately. The CDC advises calling the emergency number at once (a mobile or cordless phone is safe to use), checking that the scene is not still under threat, then checking breathing and pulse. If the person is not breathing, start rescue breaths or chest compressions, and begin CPR if there is no pulse. Use an AED if one is available.
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