The general advice I have heard for surprise lightning storms when climbing is to retreat. Since retreating quickly is not without danger itself and often is not even all that quick (I personally have spent two hours plus retreating), I was wondering if there are any other well tested strategies. I was thinking leaving most metal gear behind on the route and just waiting out the storm on a ledge could work? Are there any reported incidents of climbers getting struck by lightning with that strategy? Are there other strategies that have worked for people?
I am by no means an authority on lightning in any way. With that said, however, I have had my share of getting caught climbing in a thunderstorm, and have since tried to do some reading on the subject. The biggest hurdle to surmount here is that most lightning safety advice revolves around seeking shelter, which is often not a viable option midway up a multipitch route.
Here are some points worth considering:
- the magnitude of both voltage and current in a lightning strike is absolutely massive, and at those levels anything can conduct electricity (albeit only to a certain distance).
- you are exposed to three main mechanisms of electricity-based injury by lightning:
- direct strike
- closing a circuit
- bridging a gap for the current to jump through on its route towards the point of lowest potential (generally a lower point in the ground).
- you are also exposed to mechanical and thermal danger such as shrapnel debris due to explosive impacts and fires.
The rough points, as I understand them, are as follows:
- lightning is likely to strike the highest, sharpest point
- from there on, it will travel on the surface in all directions. Sharper edges will therefore pose the highest risk (the magnitude dissipates faster over flat surfaces and the current quickly loses energy and can no longer "jump" through the air)
- therefore, ridges, buttresses, and crack systems are the next most dangerous place to be near, and you should seek to get away from them
- standing under roofs, arches, or cave entrances increases the likelihood the current will pass through you if it jumps from the roof to the ground, so stay away from them
- wet rope is an excellent conductor and can cover a large area, increasing your risk of electrocution from an impact, you should seek to spool it up as soon as possible. Also consider this when rappelling,.
- a nearby strike may involve a concussive force, so it's important to remain secured to prevent a fatal fall
- recall: the rock will be conducting, so you should seek to minimize the surface area of the the shape formed by all points of contact between your body and the ground or wall (see page 3 in the NOLS article for an explanation of minimizing the potential difference your body offers to the "circuit")
- metal and electronics are not likely to attract lightning strikes (unless pointy and protruding), but they will definitely lead to heat burns, so you should seek to remove them from your body (carabiners, cell phones, etc.).
- thunder storms are more common in the summer months in the afternoons
- however, mountains have their own weather systems, so you should always be aware of your local weather the entire time you're out there.
As stated above, I am no authority on the subject, and welcome any criticism, corrections, and addenda to this post
Illustration of the voltage difference your multiple points of contact with the ground offer the ground current (page 3 of the NOLS link):
It's risk management. The best way to handle a storm is to get down before it starts. Check the weather and be down by noon or whenever the weather normally gets genned up.
If you're in a thunderstorm and you're very high, it is probably more dangerous to rush a technical descent than to wait out the storm or continue climbing (up or down) normally. Don't overreact. Lightning normally strikes the top or bottom as opposed to a vertical cliff face.
If you are caught in a storm, think about how to stay warm and dry enough to continue up or down safely. It will probably be colder and you'll be wetter after the storm. Your hands don't function as well when they're cold, and when you're hypothermic your judgement isn't as keen.
The small lengths of metal gear you have is not likely to affect a bolt of lightning that has traveled hundreds or thousands of feet through the air to get to the ground. As long as your hair doesn't start sticking out, don't worry about it.