LIGHTNING

Lightning Poses Some Interesting and Unique Problems for Summer Mountaineering
Generally speaking, lightning activity increases with altitude. Being below the tree line in dense forests can make it difficult to see the sky and watch approaching clouds. Above the tree line and at higher elevations, thunder rolling through canyons and valleys can make it nearly impossible to determine the direction the storm is coming from, and in some cases, even if it is in your immediate area. Finally, storm clouds can suddenly form or pass over the top of a ridge, making things nasty for the “mountain topper” in a matter of minutes.

Signs of an impending thunderstorm can include high, thin clouds streaking overhead, dark rising columns of “cotton balls” with shredded tops or dark bases with jagged, torn bottoms. When you start to hear thunder, it is time to be alert.

Knowing the right things to do during a thunderstorm can help keep your group safe and alive. One of the most common questions people ponder is: What are the odds of being struck by lightning? Although some sources have attempted to assign a statistical number to it, such as 1 in 3,000,000, it isn’t that simple. Your odds of being struck by lightning vary depending on the activity you engage in, when you engage in outdoor activities, and where you spend most of your time outdoors.

Physics of Lightning
Lightning arises from a separation of electrical charges, either between clouds or between clouds and the Earth. This separation of charge occurs when strong vertical updrafts of air act on raindrops, resulting in tremendous electrical potential differences.

The strong upward air currents may occur due to unequal solar heating of neighbouring areas, such as over freshly plowed fields and lakes. This thermal mechanism causes updrafts and resulting thunderheads and electrical activity over plains and other nonmountainous regions, but may also act in the mountains, in differential heating of air over valley floors and mountain ridges due to different ground cover. Lightning storms of this thermal origin will typically occur during the afternoon.

Another mechanism creating vertical updrafts of particular interest to mountaineers is the very presence of mountain slopes, which forces otherwise horizontally moving air to flow upwards. A significant change in weather, such as a front moving through, can cause a thunderstorm at any time of day. With appropriate moisture content in the air, electrical charge separation and consequent potential differences will result.

Strong and obvious vertical development of clouds indicates a high probability of lightning. Usually, air is a good insulator; however, in the presence of sufficiently large potential gradients, it will ionize, or break down, and conduct electrical currents quite effectively.

The lightning flash, crudely speaking, is the flow of the separated electrical charges back together, again along ionized air. Since potential gradients are largest near high and relatively sharp points, breakdown of the air and lightning will most likely occur in such locations.

The two most significant dangers from lightning are direct hits and ground currents. A direct lightning strike can kill you by causing brain damage, heart attacks or third-degree burns. Ground current from a nearby strike can severely injure you, causing deep burns and tissue damage.
Direct Hits. The first of these, as mentioned above, is most likely to occur at a sharply pointed feature such as a mountain summit, a sharp ridge or a minor summit pinnacle at the end of a ridge. A tree or a standing person is another likely target. Furthermore, a relatively small object, such as a person, is less likely to be hit when in a prominent concave terrain feature, such as a bowl, than on a convex surface, such as a knoll or large bench. The current that flows in the lightning bolt does not dissipate itself at the point of direct hit but tends to flow along the easiest paths of electrical conduction on the surface of the ground. These ground currents will be strongest near the point of direct hit, rapidly diminishing in intensity with distance. However, even well away from the direct hit, the ground currents can still be deadly.
To avoid a direct strike, get off exposed ridges and peaks. Even a few metres off a ridge is better than right on top. Avoid isolated, tall trees. A clump of small trees or an opening in the trees is safer.

Ground Currents. To avoid injury from ground currents, the climber should first of all stay out of the easy paths of current. Such easy paths include anything wet, particularly wet lichen-covered rocks, cracks and crevasses filled with water, and damp earth. Other easy paths include wet ropes, cables, and the like, along the ground. Additionally, short, straight paths through the air may be easier compared to longer paths along the ground itself.

The body is an easy path, and thus a climber should avoid the situation shown in Fig. 2 (below) or a similar one, where they are sitting in a depression in the ground across which currents might jump and harm the person. Avoid contact with the ground, squat on your pack, rope or ensuite. Electrical currents are forced through the body by potential differences that are developed along the path of the ground currents. Thus, to minimize current through the body, one’s feet should be kept close together, and the climber should be facing along, rather than across the most likely direction of current flow. His hands should be kept off the ground to prevent current from flowing directly through the vital organs, as discussed below. The person sitting, as shown in Fig., is more susceptible to injury than if they were squatting on their feet alone.

Ground currents will be small along a dry path; thus, a safe place might be under an overhang or in a cave. The danger of being at the mouth of a cave, as in Fig.1, was mentioned above – a direct spark might occur across the cave opening and pass through the body. There is also danger in being near an interior cave wall because an easy path for current may exist through the ground to the cave interior, for example, along a drainage crevasse. It is then possible for a discharge to occur from the entrance of this crevasse into the cave through a person. A small cave may give a false sense of security.

The best measure to take against being injured by lightning in the mountains is to be off the mountain; thus, a speedy descent during an impending lightning storm is appropriate.
Such descent is likely to involve rappelling, which can be exceedingly dangerous in the presence of electrical activity and rain, as a wet rope provides an easy path for current. The potential difference between the rappeller and the rock at his feet may be essentially the potential developed along the ground over the distance from the rappel anchor to the rappeller, and a large current may be easily passed along the ropes through the body. Even a minor shock may be indirectly fatal if it causes the rappeller to fall out of his rappel. Thus, rappelling involves a calculated risk. It speeds descent and escape from a dangerous area, but dramatically increases the hazard in the process.

A climber in a location exposed in the climber’s sense of the word, but moderately safe from severe lightning hazards, could experience a minor shock that would cause him to fall. Thus, he should be tied to a secure anchor. Since his tie-in rope to the anchor will act as a conductor to some extent, the rope should lie across rather than along possible paths of ground current to prevent a significant potential difference from developing between the anchor point and the climber’s position. The rope should certainly not be used for a chest sling, as this would cause any current to flow through the heart and spinal cord (See the physiology section).

Any measures taken to prevent injury from lightning will involve minimizing potential differences between different parts of the body. Thus, the best body position is the crouch. The feet should be kept close together, preferably on a small, dry rock or other insulator, such as a pack or a rope, and the hands should be kept off the ground (Important). A metal pack frame may be used to great advantage by laying it on the ground and squatting on it. Any currents would tend to pass through the metal rather than the body.

An ice axe should certainly not be worn on a pack with the blade pointing up. Still, there is no reason to discard the axe or other small metal objects, including climbing hardware, since these items may be needed later and do not attract lightning when stored in the pack or on the body. A lightning discharge is more likely to occur from the body itself than from a small object worn on the person.

Protection from a direct hit
We now consider protection from direct hits. The best solution is to be completely off the mountain. Assuming that this is possible, an advantage can be taken of the presence of a nearby prominent pinnacle or other likely spot of direct stroke. Lightning will tend to hit the pinnacle rather than a person near the pinnacle if the pinnacle is five to ten times or more than the person’s height and if the horizontal distance from the person to the peak is about half the pinnacle height. If the potential victim gets too close to the peak, their body may become an alternate path for the powerful ground currents.

If he gets into a cave, as in Fig. 2, he may be sitting in a spark gap and thus be exposed to a minor direct hit if the currents prefer to take the direct path through the air across the mouth of the cave rather than the longer path along the ground. Also, if the person moves far from under the pinnacle (more than its height), the direct hit might just as likely strike the victim as the pinnacle. A climber might find relative safety just down below a sharp ridge as well as near a peak, a pinnacle or a gendarme. The theory behind a lightning rod on a roof is related to the above; that is, it is hoped that the lightning may strike the rod rather than the roof, and the currents would then be conducted safely to the ground. Furthermore, a sharp projection may serve to discharge gradually the charge–holding a cloud over it without a lightning bolt perpetually striking, but the mountaineer should never count on this.

To avoid ground current, stay off crevices, lichen patches, or wet, solid rock surfaces, and away from gullies with streams in them. Loose rock, like talus, is safer.

Physiology
Electrical currents through the body may cause not only burns but also involuntary muscle contraction, stoppage of the heart, improper functioning of the brain and other consequent malfunctioning of the body, such as cessation of breathing. A person is not electrified after being hit by lightning, and a complete 80% of people who are struck by lightning recover.

The extent of the damage depends on the amplitude and duration of the current sent on the path of the flow through the body. When a person is struck directly, the currents are likely to be so large that no matter what the path through the body may be, the results are fatal. However, ground currents are significantly weaker, and the particular current path through the body makes a substantial difference. It is also possible for someone to be hit by lightning and be practically uninjured. For example, current from hand to hand will pass through the heart, spinal cord, and vital organs and may be fatal; however, the same current from the foot to the knee of the same leg is not as severe.

First aid may include heart massage, artificial respiration, and treatment for traumatic shock, hypothermia and burns. If a member of your party is struck by lightning, start emergency treatment immediately. If a person has no pulse or heartbeat, begin performing CPR. Treat electrical burns as you would any other type of burn. Neurological and internal injuries are possible. Mountaineers should be familiar with such treatments and be prepared to administer them.

In the mountains, you can significantly reduce your odds of being hit by lightning:
You can avoid open and exposed areas. Ridges and open fields leave you exposed. Sharp changes in terrain, such as the edge of water, the edges of a forest, or the transition from rocks to dirt, are naturally more hazardous.

Crouch near a high point at least 10 metres higher than you. Sit in the low-risk area near the base of the high point, at least 1.5 metres from cliffs or walls. If your hair is standing on end, there’s electricity in the air, and get out of there. That’s usually down the mountain. Once you choose a place to wait it out, squat with your feet close together. Keep your hands and arms away from rocks to stop the charge from flowing through your body. Stay at least 10 metres from companions, so if one is hit, another can give cardiopulmonary resuscitation.

Nearby tall objects, such as solitary trees, communication antennae, or rock spires (the tallest objects in the area), serve as natural lightning rods. You can find a location with trees of uniform height or an area with low brush and bushes. Never seek shelter directly under a tree. If you cannot find any shelter at all, say when you are above the tree line, get as low as possible.

If in a region of high lightning danger, individuals should not wait out the storm huddled together. Spread out at least 20 feet, as lightning can jump this far and injure everyone in a tight group. The survival of one person whose heart or breathing has been stopped by a stroke of lightning will depend critically on prompt action by companions, and it is unlikely that a group of separated persons will be knocked unconscious simultaneously.

If you have metal gear, such as carabiners, picks, or crampons, remove them and set your gear away from you. Sit on top of your pack if you have one, with your feet on the ground, crouched down with your eyes closed and your hands over your ears. Sight and hearing injuries are prevalent among lightning strike victims and near-strike injuries. Please don’t lie prone on the ground; this position is no longer recommended as safe.

Lightning can originate from six to eight miles away from its last origin, so it is possible for a “bolt from the blue” on the edge of a storm. This is why, if you wait until you see lightning, it may already be too late to take action. If your hair stands on end, you feel a tingling sensation, or if the area around you appears electrified, lightning may be ready to strike. Make yourself the smallest possible target and attempt to minimize your contact with the ground. Hold your breath; some people have been seriously injured when they breathe in the superheated air that surrounds and is expanding out from a lightning bolt. 
Could you wait at least 30 minutes after the lightning and thunder have stopped before resuming activity?