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Harvard Commentaries
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Harvard Commentaries
Reviewed by the Faculty of Harvard Medical School


Man to Man Man to Man
 

Stormy Weather -- Shocking Summer Hazards


January 24, 2013

By Harvey B. Simon M.D.

Harvard Medical School

Speaking man-to-man, let me shed my anonymity, even at the cost of my reputation. I love to run. Nothing disreputable about that, but it may seem strange that I've run every day since October 30, 1978. Winter in New England has sometimes put my resolve to quite a test, but you may be surprised to learn that summer has produced the greatest threats to my survival on the road. That's because summer is thunderstorm season. While most storms are harmless, lightning is a terrible hazard for a guy stranded on a country road far from home.

Self-preservation has taught me a thing or two about lightning, so I'd like to share some survival tips with you.

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What Causes Thunderstorms?

Thunderstorms develop when warm moist air collides with cool dry air. Summer heat and humidity provide the former, and a cold front or ocean breeze provides the latter.

The National Weather Service reports that about 100,000 thunderstorms occur in the United States each year. Although thunderstorms can occur at any time of the year in any part of the country, they are most common in summer, and most prevalent in the Midwest and Southeast.

The average thunderstorm is only about 15 miles across and lasts just 30 minutes. Despite their small size and short duration, every storm is potentially dangerous. Water and wind produce many woes, but the most spectacular hazard is lightning.

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The Hazards of Lightening

"Thunder is impressive" wrote Mark Twain, "but it is lightning that does the work."

Every thunderstorm contains lightning. Lightning that stays in the clouds is harmless, but the current that flows from cloud to ground is very dangerous.

Cloud-to-ground strikes occur about 30 million times each year in the United States; each bolt contains 3 million to 200 million volts of electricity.

Lightning is bright and it's also very hot. A bolt can reach a temperature of 50,000 degrees Fahrenheit — hotter than the surface of the sun — within a split second. The rapid heating and cooling of the air near a lightning bolt sets the air vibrating, which produces a thunderclap.

Shocking Facts

  • On average, 82 Americans are killed by lightning each year; 85% are men and 68% are between the ages of 15 and 44.
  • More than 90% of lightning deaths occur between May and September. These are mostly in the late afternoon and early evening.
  • More than half the victims are struck during outdoor recreational activities, such as golf, while 25% are hit during work, such as farming or construction.
  • About 30% of people struck by lightning die, mostly because the electrical energy scrambles the heart's electrical system, halting its normal pumping action.
  • 74% of survivors have permanent disabilities.

Although direct strikes are the most serious, side flashes from lightning that first strike a nearby building or tree can also be lethal. Currents can even splash from person to person, which accounts for the multiple deaths often associated with lightning strikes.

Like other forms of high voltage current, lightning can cause burns, deep tissue injuries, damage to the nervous system and cardiac arrest. Burns are usually surprisingly superficial and relatively mild because most of the energy is carried away from the body. But even though people may live to tell about being struck by lightning, many have headaches, dizziness, memory loss and other neurological symptoms that are similar to a concussion.

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Protect Yourself From Lightening

People think of lightening as the "bolt from the blue" — an unpredictable and unavoidable hazard. Lightning is indeed hazardous, but like most "accidents," it's both predictable and avoidable. No man can prevent thunderstorms, but every man can protect himself from lightning. Here are some tips:

  • Be alert for weather forecasts and storm warnings whenever you participate in outdoor activities, especially from May through September. Inexpensive battery-operated National Oceanic Atmospheric Administration (NOAA) weather radios can keep you posted wherever you are.
  • Take precautions as soon as you hear thunder. Don't be lulled into a sense of false security because the storm is distant or because it is not yet raining. Lightning can strike — and kill — from as far as 10 miles away, and it can precede rainfall.
  • Seek shelter as soon as possible. Don't tempt fate by finishing your round of golf or planting that final shrub during a thunderstorm. Get inside, but stay away from windows and exterior doors. Turn off appliances and electrical devices and avoid contact with the plumbing system.
  • Don't make the mistake of assuming that it's safe to venture out after lightning has struck. Contrary to widespread belief, lightning can strike twice in the same location. Remain inside until the storm passes.
  • If you can't get into a building, seek shelter in a vehicle such as a car or bus. Avoid metal shelters and sheds.
  • If no shelter is available, take precautions outdoors. Avoid high ground and water. Stay away from trees, lamp poles and other tall objects, as lightning that strikes them can splash over to you. Crouch down so you are not the tallest object in the area, but don't maximize your contact with the ground by lying down. If you are on a slope or hill, face downhill. Avoid metal objects, such as fences, tools, umbrellas and golf clubs.

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Flash Floods

Although lightning is the flashiest part of a summer storm, the flash floods that often accompany severe storms actually kill more Americans — about 140 a year. A slow-moving storm that packs heavy rainfall can trigger a flood within minutes or hours. Just six inches of fast-flowing water can knock you off your feet. Taking refuge in a car is not much safer; two feet of fast water will float most vehicles.

If you hear a flash-flood warning, get to high ground as quickly as possible. Stay away from culverts and gulleys during and after rainstorms. If you encounter flood waters, turn back at once; don't ever try to walk, swim or drive through fast-moving waters.

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Wind and Hail

Winds can top 100 miles per hour and are responsible for most storm-related wind damage. But in some areas of the country, tornadoes — violently rotating columns of air extending from a thunderstorm to the ground that can pack winds of 250 miles per hour — are a huge worry. If you live in a community at risk, you should have a plan to find shelter or evacuate. And you should also have a first-aid kit, an emergency supply of water and non-perishable food, and necessary medications on hand.

Hail forms when updrafts carry drops of water to cool altitudes, where they freeze. When the particles become too heavy, they fall to earth. Hail produces enormous economic damage to property and crops, but personal injuries are uncommon.

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Other Issues

Asthma attacks are among the less well-publicized consequences of thunderstorms. Folks with seasonal allergies and allergic asthma are at risk, probably because storms stir up pollen and spores.

The falling barometric pressure can also trigger migraine headaches and might even worsen episodes of sleep apnea.

And while some people view thunderstorms as great outdoor theatre, others can become quite upset and anxious. But if you understand what causes all the ruckus and how to prevent injury, you should be able to stay calm in the face of stormy skies.

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Harvey B. Simon, M.D. is an Associate Professor of Medicine at Harvard Medical School and a member of the Health Sciences Technology Faculty at Massachusetts Institute of Technology. He is the founding editor of the Harvard Men's Health Watch newsletter and author of six consumer health books, including The Harvard Medical School Guide to Men's Health (Simon and Schuster, 2002) and The No Sweat Exercise Plan, Lose Weight, Get Healthy and Live Longer (McGraw-Hill, 2006). Dr. Simon practices at the Massachusetts General Hospital; he received the London Prize for Excellence in Teaching from Harvard and MIT.

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