Farmers warned against flirting with lightning

2013-07-03T17:45:00Z Farmers warned against flirting with lightningBy Jane Fyksen, Agri-View Minnesota Farm Guide
July 03, 2013 5:45 pm  • 

Farmers are famous for tempting fate – and Mother Nature. Everybody has pushed to finish up field operations ahead of incoming storms; however, the National Weather Service reminds us that it’s your behavior when thunderstorms are rolling in that determines your personal risk of being struck by lightning. If you hear thunder, lightning is close enough to strike you.

June 23 to 29 was Lightning Safety Week. The warning: “When Thunder Roars, Go Indoors!” The United States averages more than 23 million cloud-to-ground flashes of lightning every year.

When you hear thunder immediately move to safe shelter, which according to the National Weather Service is a “substantial building with electricity or plumbing, or an enclosed, metal-topped vehicle with windows up.”

Too many people wait far too long to get to a safe place when thunderstorms approach; sometimes tragically, their delay has resulted in lightning injury or death. Many also do not wait long enough after the heaviest portion of the storm has passed to return outdoors. The best way to protect yourself from lightning is to avoid the threat.

Thunder can be heard for a distance of about 10 miles from the lightning strike. Thunder is created when the lightning discharge hearts the air rapidly, causing it to expand. The temperature of the air in the lightning channel can reach 50,000 degrees – five times hotter than the surface of the sun. Immediately after the flash, the air cools and contracts quickly. It’s this quick expansion and contraction that creates thunder. It takes the sound of thunder about five seconds to travel a mile, but again, if you can hear thunder, chances are you are within “striking distance” of the storm.

In general, a significant lightning threat extends outward from the base of a thunderstorm cloud about 6 to 10 miles. Therefore people should be in a safe place when a thunderstorm is 6 to 10 miles away. And because electrical charges can linger in clouds after a thunderstorm has passed, experts agree people should wait at least 30 minutes after a storm before resuming activities. “Heat lightning,” it should be noted, is simply lightning from a distant thunderstorm that is just too far away to see cloud-to-ground flashes and hear the accompanying thunder. It’s not a different kind of lightning.

If you are caught outside with no safe shelter nearby, reduce your risk by: avoiding open fields, getting off an elevated area, never lying flat on the ground, getting away from an isolated tree, never using a rocky overhang for shelter, getting out and away from water (the vast majority of lightning injuries and deaths are in boats), and staying away from objects that conduct electricity such as wire fences, power lines and windmills. Indoors, stay off corded phones (i.e., cell phones and cordless telephones are safe), computers and other electrical equipment that put you in direct contact with electricity. Avoid plumbing like the shower and kitchen sink. Do not lie on a concrete floor or lean against a concrete wall either when it’s lightning. Picnic shelters and small sheds are not considered safe havens from lightning strikes. Neither are porches and baseball dugouts.

It’s a “myth” that rubber tires on a car protect you from lightning by insulating your from the ground. It’s actually the metal roof and sides that protect you – not the tires. When lightning strikes a vehicle, it goes through the metal frame into the ground. So do not lean on the doors during a thunderstorm and avoid contact with metal portions of the car.

Lightning enters a structure three ways – a direct strike, through wires or pipes that extend outside the structure and through the ground. Once in a structure, it can travel through the electrical, phone, plumbing and radio/television reception systems. It also can travel through any metal wires or bars in concrete walls or floors.

If you are caught outdoors with no safe escape, such as in the woods, stay near a lower stand of trees (i.e., avoid the tallest ones), or shelter in a low area, but not one in which you would be standing in water. Just remember that “height, pointy shape and isolation” are the dominant factors controlling where a lightning bolt will strike.

People can and do survive lightning strikes, however, oftentimes, their heart or breathing may have stopped and CPR is needed to revive them. It’s a misnomer that lightning victims carry an electrical charge; it’s safe to touch them and provide emergency medical help. Some victims may appear to have a delayed death a few days later if they are resuscitated but have suffered irreversible brain damage.

During the last 30 years, the U.S. has averaged about 54 “reported” lightning fatalities a year; it’s actually higher. Only about 10 percent of people struck by lightning are killed, leaving 90 percent with various degrees of disability. While the odds of being struck by lightning in a given year are one in 775,000, the odds of being struck in your lifetime (estimated at 80 years) is one in 10,000. Estimating that 10 people (immediate family and friends) are affected for every one person struck, the odds you will be affected by someone being struck is one in 1,000.

Victims are struck in three ways. A direct strike typically occurs in open areas. While not as common as other ways people are struck by lightning, this is potentially the most deadly. Current moves through the body and just over the skin (called “flashover”), creating burns. A side flash (also called a “side splash”) occurs when lightning strikes a taller object near the victim and the current jumps to the victim. Side flashes occur when a victim is within a foot or two of the object struck. Most often, side flash victims have taken shelter under a tree. The third way is ground current; an object is hit and the energy travels outward along the ground. Anyone outside near a lightning strike is potentially a victim of ground current. In addition, ground current can travel in garage floors. Ground current causes the most lightning deaths and injuries. It also kills a lot of livestock. Lightning can spread out some 60 feet after striking the ground.

Lightning injury is primarily to the nervous system, i.e., brain and nerves. Serious burns seldom occur. People who do not suffer cardiac arrest at the time of the incident may suffer lesser symptoms, which often clear during a few days. The list is long, from: muscle soreness, headache, nausea and other post-concussion types of symptoms; mild confusion; dizziness and balance problems; longer-term problems like slower reaction time, irritability and personality change, forgetfulness, headaches that do not resolve, chronic pain from nerve injury, ringing in the ears, trouble sleeping, depression and more.

Every year, lightning causes, on average, 24,600 forest, grass and house fires. While most fires are outdoors, lightning starts about 4,400 house fires every year. Lightning rods, and the accompanying protection system, do not prevent lightning from striking a structure but rather intercept the strike, providing a conductive path for the electrical discharge to follow and disperse the energy safely into the ground. It’s important components be properly installed and bonded.

Copyright 2015 Minnesota Farm Guide. All rights reserved. This material may not be published, broadcast, rewritten or redistributed.

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