LIGHTNING STRIKE

Published on 14/03/2015 by admin

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Last modified 22/04/2025

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LIGHTNING STRIKE

Lightning strikes the earth at least 100 times per second during an estimated 3,000 thunderstorms per day. Fortunately, the odds of being struck by lightning are not very great. Still, approximately 60 persons per year are victims of fatal strikes in the United States. The wise traveler respects thunderstorms and seeks shelter at all times during a lightning storm.

Lightning is the direct-current electrical discharge associated with a thunderstorm; it releases an initial charge (the vast majority of which travels from ground [positive] to cloud [negative]) of approximately 30 million volts to neutralize a potential difference (within a hundredth to a ten-thousandth of a second) of 200 million to a billion volts. A lightning flash may be made up of multiple (up to 30) strokes, which causes lightning to seem to flicker. Each stroke lasts less than 500 milliseconds. The diameter of the main stroke is 2½ to 3 in (6 to 8 cm); the temperature has been estimated to be anywhere from 14,432°F to 90,032°F (8,000°C to 50,000°C—four times as hot as the surface of the sun). Within milliseconds, the temperature falls to 3,632°F to 5,432°F (2,000°C to 3,000°C).

Thunder, which is always present with lightning, is attributed to the nearly explosive expansion of air heated and ionized by the stroke of lightning. To estimate the approximate distance in miles from your location to the lightning strike, time the difference in seconds between the flash of light and the onset of the thunder, and divide by five.

Lightning can injure a person in five ways:

1. Direct hit, which most often occurs in the open.

2. Splash, which occurs when lightning hits another object (tree, building). The current seeks the path of least resistance, and may jump to a human. Splashes may occur from person to person, or from a metal fence.

3. Contact, when a person is holding on to a conductive material that is hit or splashed by lightning.

4. Step (stride) voltage (or ground current), when lightning hits the ground or an object nearby. The current spreads like waves in a pond.

5. Blunt injury, which occurs from the victim’s own muscle contractions and/or from the explosive force of the shock wave produced by the lightning strike. These can combine to cause the victim to be thrown, sometimes a considerable distance.

When lightning strikes a person directly, splashes at him from a tree or building, or is conducted along the ground, it usually largely flows around the outside of the body (flashover phenomenon), which causes a unique constellation of signs and symptoms. The victim is frequently thrown, clothes may be burned or torn (“exploded” off by the instantaneous conversion of sweat to steam), metallic objects (such as belt buckles) may be heated, and shoes removed. The victim often undergoes severe muscle contractions—sufficient to dislocate limbs. In most cases, the person struck is confused and rendered temporarily blind and/or deaf. In some cases, there are linear (1½ to 2 in, or 1.3 to 5 cm, wide, following areas of heavy sweat concentration), “feathered” (fernlike; keraunographism; Lichtenberg’s flowers—cutaneous imprints from electron showers that track over the skin) (Figure 215, A), or “sunburst” patterns of punctate burns over the skin (Figure 215, B), loss of consciousness, ruptured eardrums, and inability to breathe. Occasionally, the victim ceases breathing and suffers a cardiac arrest. Seizures or direct brain damage may occur. Eye injuries occur in half of victims.

Figure 215 A, Ferning lightning burn. B, Punctate (starburst) lightning burn.

A victim struck by lightning may not remember the flash or thunder, or even recognize that he has been hit. The confusion, muscle aches, body tingling, and amnesia can last for days. With a more severe case, the skin may be mottled, the legs and/or arms may be paralyzed, and it may be difficult to locate a pulse in the radial (wrist) artery (see page 33), because the muscles in the wall of the artery are in spasm. First-, second-, or third-degree skin burns may be present. Broken bones are not uncommon.

If a person is found confused, burned, or collapsed in the vicinity of a thunderstorm, consider the possibility that he was struck by lightning. The victim is not “electrified” or “charged”—you will not be jolted or stunned if you touch him.

1. Maintain the airway and assist breathing (see page 29). Continue to perform artificial respiration and cardiopulmonary resuscitation (CPR) (see page 32) until sophisticated help can be obtained. Victims of lightning strike may have paralysis of the breathing mechanism for a period of 15 to 30 minutes, and then make a remarkable recovery. A seemingly lifeless individual may be saved if you breathe for him promptly after the injury. Do not assume that dilated or nonreactive (to light—see page 36) pupils are a sign of death, because they may represent direct injury to the eye(s).

2. Assume that the victim has been thrown a considerable distance. Protect the cervical spine (see page 37).

3. Examine the victim for any other injuries and treat accordingly.

4. Transport the victim to a hospital.

5. If you are in the vicinity of a thunderstorm, seek shelter for the victim and yourself. Lightning can strike twice in the same place!

LIGHTNING AVOIDANCE

1. Know the weather patterns for your area. Don’t travel in times of high thunderstorm risk. Avoid being outdoors during a thunderstorm. Carry a radio to monitor weather reports. Lightning can lash out from many miles in front of a storm cloud, in seemingly clear weather. If you calculate (see above) that a nearby lightning strike is within 3 miles (5 km) of your location, anticipate that the next strike will be in your immediate area. The “30-30 rule” specifies that if you see lightning and count less than 30 seconds before hearing thunder, seek shelter immediately. Since thunder is rarely heard from more than 10 miles away, if you hear thunder, it is best to curtail activities and seek shelter from lightning. Do not resume activities outdoors for at least 30 minutes after the lightning is seen and the last thunder heard.

2. If a storm enters your area, immediately seek shelter. Enter a hard-roofed auto or large building, if possible. Tents and convertible autos offer essentially no protection from lightning. Tent poles are lightning rods. Metal sheds are dangerous because of the risk of side splashes. Indoors, stay away from windows, open doors, fireplaces, and large metal fixtures. Inside a building, avoid plumbing fixtures, telephones, and other appliances attached by metal to the outside of the building.

3. Do not carry a lightning rod, such as a fishing pole or golf club. Avoid tall objects, such as ski lifts and power lines. Avoid being near boat masts or flagpoles. Do not seek refuge near power lines or tall metal structures. If you are in a boat, try to get out of the water. If you are swimming in the water, get out. Do not stand near a metal boat. Insulate yourself from ground current by crouching on a sleeping pad, backpack, or coiled rope.

4. Move off ridges and summits. Thunderstorms tend to occur in the afternoon, so attempt to summit early and be heading back down by noon. In the woods, avoid the tallest trees (stay at a distance from the tree that’s at least equal to the tree’s height) or hilltops. Shelter yourself in a stand of smaller trees. Avoid clearings—you become the tallest tree. Don’t stay at or near the top of a peak or ridge. Avoid cave entrances. In the open, crouch down or roll into a ball.

5. Stay in your car. If it is a convertible, huddle on the ground at least 50 yards (46 m) from the vehicle.

6. If you are part of a group of people, spread the group out so that everyone isn’t struck by a single discharge.

7. If your hair stands on end, you hear high-pitched or crackling noises, or see a blue halo (St. Elmo’s fire) around objects, there is electrical activity near you that precedes a lightning strike. If you can’t get away from the area immediately, crouch down on the balls of your feet and keep your head down. Don’t touch the ground with your hands.

8. The StrikeAlert Personal Lightning Detector (Outdoor Technologies, Inc.) is the size and configuration of a pager and uses an audible warning and LED display to show the wearer how far away lightning is striking and if a storm is approaching or leaving.

TORNADO AVOIDANCE

1. Watch the cloud formations in a stormy sky. If you see revolving, funnel-shaped clouds, you are in danger.

2. Take shelter immediately. The best location is an underground cave or concrete structure. Do not remain in a tent or camper.

3. If you are caught outside in open country, hunker down or lie flat in a depression, ditch, culvert, or ravine. Cover your head with your arms.

4. Do not try to outrun a tornado. There is no way to predict when it will change direction.

WHAT TO DO IN AN EARTHQUAKE

If you are caught in an earthquake in a wilderness setting, do the following:

1. Seek a safe location, out of the path of a rockfall, mudslide, or snow avalanche. If you can, move into a clearing away from buildings, trees, and power lines. If the ground shaking is extreme, position yourself on your hands and knees.

If you are in a moving vehicle, drive to a clearing, exit the vehicle, and stay next to it until the shaking stops. If something collapses on it while you are inside, you may be crushed. If you are outside the vehicle, it may compress and create a safe space adjacent to it.

If you are indoors, stay put until you are certain that it’s safe to go outside. Move away from glass windows. Curl into a fetal position, and position yourself next to something that can compress, but not crush, and thereby protect you by leaving an adjacent void. If you are in a bed during an earthquake, roll off the bed and remain next to it. Do not remain in a doorway, and try to stay off stairs.

2. Eliminate any obvious fire hazards. If you are in a cabin supplied with natural gas, turn it off at the source if there is any odor or you believe there might be a leak.

3. Be prepared for aftershocks.

4. Secure a supply of drinking water. Be certain that you are prepared for a period of time without electrical power.

5. Prepare a shelter, store sufficient food, and locate equipment necessary for survival. Keep first-aid supplies and a flashlight within easy reach.

VOLCANOES

The eruption of a volcano can be a cataclysmic event. Since recorded time, pyroclastic flows (described below) have killed the greatest number of people, while flying solid objects (called “tephra” by volcanologists) thrown out by the volcano are the most frequent killers. Usually, when an explosive volcano erupts, a cloud of gas, ash, and lava fragments rises up into the atmosphere. If the eruption cloud becomes more dense than the surrounding air, it may fall back toward the ground, propelled by the forces of gravity. This can lead to formation of an incredibly hot (more than 1,500°F), high-speed (faster than 180 miles per hour) avalanche of ash, volcanic gases, lava fragments, and heated air, which is called a pyroclastic flow. The extreme temperatures may also generate gale-force winds. Because of the forces and temperatures involved, no living being caught in this infernal river can survive. Most human victims die from suffocation, exposure to the heat, or burial under the volcanic debris. Anyone who travels in the vicinity of an active volcano should be aware of the risks and have a well thought out, realistic evacuation plan.

SNOW AVALANCHES

Some of the factors that influence a buried victim’s chances for survival are time buried, depth buried, clues on the surface (to facilitate location of the victim and rescue), rescue equipment, injury, ability to fight the avalanche, body position, snow density, presence of air (breathing) pocket and size of air pocket, and luck. A victim who is uninjured and able to fight on the downhill ride usually has a better chance of ending up only partly buried, or if completely buried, a better chance of creating an air pocket for breathing. A victim who is severely injured or knocked unconscious is like a rag doll being rolled, flipped, and twisted. Being trapped in an avalanche is a life-and-death struggle, with the upper hand going to those who fight the hardest.

Avalanches kill in two ways. First, serious injury is always possible in a tumble down an avalanche path. Trees, rocks, cliffs, and the wrenching action of snow in motion can do horrible things to the human body. Second, snow burial causes asphyxiation (either obstructed airway or exhausted oxygen supply). A very small percentage of avalanche victims succumb to hypothermia, probably because they succumb to injuries or asphyxia before they have a chance to become sufficiently hypothermic to expire.

The problem of breathing in an avalanche does not start with being buried. A victim swept down in the churning snow has an extraordinarily hard time breathing. Inhaled snow clogs the mouth and nose; asphyxiation occurs quickly if the victim is buried with the airway already blocked. Snow that was light and airy when a skier carved turns in it becomes viselike in its new form.

Snow sets up hard and solid after an avalanche. It is almost impossible for victims to dig themselves out, even if buried less than a foot deep. Hard debris makes recovery very difficult in the absence of a sturdy shovel. The pressure of the snow in a burial of several feet sometimes is so great that the victim is unable to expand his or her chest to draw a breath. Warm exhaled breath freezes on the snow around the face, eventually forming an ice lens that cuts off all airflow.

Another factor that affects survival is the position of the victim’s head; that is, whether the victim is buried face up or face down. The most favorable position is face up. Data from a limited number of burials show that the victim is twice as likely to survive if buried face up rather than face down. If buried face up, an air pocket forms around the face as the back of the head melts into the snow; if buried face down, an air pocket cannot form as the face melts into the snow.

A completely buried victim has a poor chance of survival. Survival is interrelated with both time and depth of burial. Survival probabilities diminish with increasing burial depth. To date, no one in the United States who has been buried deeper than 7 ft (2.1 m) has been recovered alive.

Time is the true enemy of the buried victim. In the first 15 minutes, more persons are found alive than dead. At 30 minutes, an equal number are found dead and alive. After 30 minutes, more are found dead than alive, and the survival rate continues to diminish. In favorable circumstances, buried victims can live for several hours beneath the snow; therefore rescuers should never abandon a search prematurely. In 2003, two snowshoers caught near Washington’s Mt. Baker survived burials of 22 and 24 hours. Such long survival times are a reminder that no rescue should be abandoned prematurely on the thought that the victim is dead.

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