by Donald L. Fink
Do you know what lightning smells like? If you do, you could be one of the few who have escaped a very close call with death. Last summer, Bonnie and I were afforded an opportunity to experience the smell of lightning up close.
We had driven across Carson Pass, beyond Red Lake and toward Hope Valley. It's been our practice for many years to spend at least one day out of each camping trip visiting some part of the Sierras where we've never been. We usually make a short day hike to some randomly chosen spot for lunch. Just before the Valley, we turned off the highway and drove along a dirt road to the southwest, near the peaks along the left side of Highway 88. Driving as far as our two wheel drive truck would take us, we parked and began a leisurely walk along the road toward the top of one of the taller mountains.
Twenty feet from our truck, we disturbed a young cinnamon colored black bear eating a bag of Chips Ahoy. It concerns me when I see wild animals (especially bears) eating left-over human foods, but perhaps that's another discussion altogether. Further along the dirt road, we encountered a beautiful cascading waterfall. The stream was running high for this time of year, so it was most enjoyable to watch. The water tumbled down perhaps sixty feet of rough lava rocks before reaching the base in a white froth of activity.
Beyond the stream, we crossed an open space of a quarter of a mile or more as we climbed steadily up the now unimproved and unused logging road with the mountain peak to our left. White puffy cumulus clouds appeared over the peak from time to time and drifted overhead and eastward, adding variety to an otherwise solid blue sky.
At about two-thirds of the way up the mountain, we came to a switch-back that traversed the mountain in the other direction, back through the clear area for another quarter of a mile as the road made its way to what appeared to be the top. We stood for a moment, studying the road, the open space, and the clouds, and finally decided to stay where we were for lunch.
At the switch-back, the mountain was creased by another stream where a stand of trees stood forming a barrier for the road. We didn't have any particular goal for our hike, so this spot was as good as any for a rest. Besides, the view of Hope Valley from this vantage point was spectacular.
As we sat on the slope facing east and admiring our view and sampling our sandwiches, the puffy white cumulus clouds behind us continued to stretch their way over the peak. Some were extending themselves beyond the light and lofty cumulus stage and were becoming dark and threatening. At one point during our stay, we turned to notice the cumulonimbus clouds behind us, and finally began to understand our situation. A potential thunderstorm was approaching, and we were without anywhere to go. Every direction of travel required that we cross at least a quarter of a mile of open space. As we assessed our options, we realized that we were probably in the best possible position given the situation. We were in a grove of small trees with larger trees around us in all directions. We had protection from any possible rain and we were not near the tallest objects around.
As we sat, the rain began. Light at first, then hard and pounding a short time later. The rain drops were very cold, almost frozen, telling us they came from a very high altitude; a sure sign that they were associated with turbulent clouds.
We donned our rain gear and verified that our cameras were tucked safely away in their waterproof sacks. As we sat comfortably on the ground, the almost frozen rain pelted us and the clouds sailed overhead.
The lightning struck somewhere behind us up-slope with a blinding flash. There was no time to count the seconds before the thunder arrived because it happened simultaneously. Fifteen seconds later we could smell the ozone. It burned our noses as we sat in the freezing rain, waiting for the next flash of light. Fortunately the next strike never came. There was but one great stroke of light on our side of the mountain, and then the storm was gone as rapidly as it had approached.
Sitting for awhile on the rain soaked earth, we were happy the storm had gone and left us unharmed. We began our slow walk back down the mountain without talking. I was thinking this was a great day to be alive, and I wondered what the bear had thought about the lightning.
Lightning strikes when electrical charges in the atmosphere become significantly different from the electrical charge in the earth. Usually the atmospheric charges are associated with thunderstorm activity, and the charge within the lower portions of storm clouds are negative with respect to the earth. That is, there are more electrons in the lower portion of cumulonimbus clouds than there are in the earth directly under them.
Several theories exist as to why this occurs, and there is probably at least some truth in nearly all of them. One theory that seems to hold more promise than others explains that electric charges build because of the thermoelectric effects of water at and near the point of freezing.
When an object freezes at an uneven rate, free ions - especially positive ones - tend to migrate to the coldest part of the object. Consider, for example, a hailstone as it is in the process of freezing inside a cumulonimbus cloud. Negative ions are less mobile in ice than positive ions, so they tend to remain where they are within the hail stone. Positive ions, however, migrate to the coldest part of the hailstone which is the outer shell. As the hailstone moves up and down through the turbulent column of air within the cloud, it eventually becomes too heavy to remain aloft and plunges downward through the cloud. In the lower portions of the storm, the hailstone, which carries a positive charge on its outer shell, occasionally comes into contact with super-cooled water. The super-cooled water is actually colder than the hailstone, so the positive ions migrate to the water, leaving the hailstone with an overall negative charge. The water continues upward through the cloud while the hailstone travels downward. Eventually, the thunder cloud ends up with its upper region carrying an overall positive charge and the lower region sustaining a negative charge. It's when this potential difference becomes too great to remain insulated by the atmosphere that lightning occurs in the form of cloud-to-cloud or cloud-to-ground discharges.
Testing this theory in the laboratory has yielded mixed information; it doesn't always work. Other theories offer other explanations, and they too offer mixed results in the laboratory. Probably there is some truth in all of them, and more than one mechanism is present in most storms
While this may be a fascinating academic discussion, it really makes little difference to the observer on the ground. If you're standing in the open in the forest and there's a menacing thunder cloud overhead, and your hair is standing straight out while the rest of your body tingles with static electricity, it makes little real difference why you're about to be struck by lightning. The simple fact is, you're in serious trouble. Lightning strikes kill and injure people and livestock every year in California.
What can we do to prevent lightning from injuring us? There is very little that can be done to prevent possible injury, but there are many things that may reduce the chance of injuries occurring.
First, when you're traveling in the forest, pay attention to your surroundings. Thunderstorms occur frequently in the summer, and can surprise you if you're not attentive. Storms may build along a ridge behind you or beyond your sight then blow over to your location. Thunderstorms occur most frequently in the afternoons in the Sierras. Plan your outings accordingly. If you're planning to be on a mountain peak, try to be there early in the day. Be ready to abandon or postpone your outing if a storm seems likely to occur.
Second, if you're caught outside during a lightning storm, don't be conspicuous. Do not be the tallest object around. Lightning will almost always choose the shortest path for discharge. Don't be caught in the middle. Stay away from the peaks of mountains, ridge lines, cliffs, and any surface area of the earth that makes a sharp point, or is in some other way "conspicuous". Stay away from power and telephone lines. Lightning can strike at some location away from you and transmit through the lines. This applies to electrical devices at home too. Do not use telephones or two-way radios during lightning activity. Cordless and cellular phones are OK because they're not plugged directly into outside lines.
Third, if you're outside and a storm appears to be likely, seek shelter. If suitable shelter is not readily available, seek lower ground. Find low spots along the earth and stay there. Remember that because no lightning has occurred does not mean that there is no danger. Someone's got to be first. Take shelter before lightning occurs when possible.
Some survivors of lightning strikes have reported that, just before the strike, they experienced the sensation that static electricity was all around them; giving them a tingling feeling all over their bodies. Their hair stood out, and some people even reported seeing a pale blue light all around. These phenomena are all consistent with the currently understood physics of lightning, and should be acted upon without delay.
Many experts agree that the safest course of action is to immediately crouch as low as possible while standing on the balls of your feet. The idea is to make yourself as low as possible while making as little contact with the ground at the same time. There's little point in trying to run, because there won't be time. From most accounts, you have something less than two seconds before a strike may occur. Not all occurrences of the sensation of static electricity precede lightning strikes. My father imparted a story to me last summer about being in an aluminum boat on Lake McClure during a period of heavy cumulus activity. He remembers the sensation of static electricity all around, but denies any recollection of nearby lightning discharges.
While a story about lightning may make interesting reading, it's important to keep the notion of danger in perspective. While it's true that lightning kills people every year, it's also important to understand how minimal the risk is. There are many things in the Sierras that will kill human beings. Deaths can range from natural causes - heart attacks and illness - to meteor strikes. There are many dangers in the forest that are more real. Automobile accidents, self inflicted injuries such as falling off rocks, gunshot wounds, skiing accidents, all inflict more injuries each year than lightning. My wife and I were probably at more risk from the black bear we encountered than from the lightning, and we don't consider wildlife in the Sierras to represent a significant hazard.
Any endeavor is accompanied by risk. Lightning, while imposing a risk to our lives every time we venture into the wilderness, should be recognized for the minor danger that it really is. When viewed like any other manageable risk, lightning becomes a relatively small part of our overall adventure in life.
From the June 1996 issue of The Interpreter.
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