U.S. National Park Ranger Roy Sullivan Record For Being Struck By Lightning Seven Times
January 19, 2012 by staff
U.S. National Park Ranger Roy Sullivan Record For Being Struck By Lightning Seven Times, Lightning strikes are electrical discharges caused by lightning, typically during thunderstorms.
Humans can be hit by lightning directly when outdoors. Contrary to popular notion, there is no ‘safe’ location outdoors. People have been struck in sheds and makeshift shelters. However, shelter is possible within an enclosure of conductive material such as an automobile, which is an example of a crude type of Faraday cage.
World map showing frequency of lightning strikes, in flashes per km² per year (equal-area projection). Combined 1995-2003 data from the Optical Transient Detector and 1998-2003 data from the Lightning Imaging Sensor.
The Eiffel Tower as a colossal lightning conductor. Photograph taken at 21.02 1902-06-03
An estimated 24,000 people are killed by lightning strikes around the world each year and about 240,000 are injured. In the U.S., between 9 and 10% of those struck die, for an average of 40 to 50 deaths per year (28 in 2008). In the United States, it is the #2 weather killer (second only to floods). The odds of an average person living in the U.S. being struck by lightning in a given year is 1/500,000.
U.S. National Park Ranger Roy Sullivan has the record for being struck by lightning the most times. Sullivan was struck seven times during his 35 year career. He lost the nail on one of his big toes, and suffered multiple injuries to the rest of his body.
Lightning strikes injure humans in several different ways:
Direct strike, which is usually fatal.
Contact injury, when the person was touching an object that was struck
Side splash, when current jumped from a nearby object to the victim
Ground strike, current passing from a strike through the ground into a nearby victim. A strike can cause a difference of potential in the ground (due to resistance to current in the Earth), amounting to several thousand volts per foot.
Blast injuries, either hearing damage or blunt trauma by being thrown to the ground.
Lightning strikes can produce severe injuries, and have a mortality rate of between 10 and 30%, with up to 80% of survivors sustaining long-term injuries. These severe injuries are not usually caused by thermal burns, since the current is too brief to greatly heat up tissues, instead nerves and muscles may be directly damaged by the high voltage producing holes in their cell membranes, a process called electroporation.
In a direct hit the electrical charge strikes the victim first. If the victim’s skin resistance is high enough, much of the current will flash around the skin or clothing to the ground, resulting in a surprisingly benign outcome. Metallic objects in contact with the skin may concentrate the lightning strike, preventing the flashover effect and resulting in more serious injuries. At least two cases have been reported where a lightning strike victim wearing an iPod suffered more serious injuries as a result. However, during a flash the current flowing around the body will generate large magnetic fields, which may induce electrical currents within organs such as the heart. This effect might explain the cases where cardiac arrest followed a lightning strike that produced no external injuries.
Splash hits occur when lightning prefers a victim (with lower resistance) over a nearby object that has more resistance, and strikes the victim on its way to ground. Ground strikes, in which the bolt lands near the victim and is conducted through the victim and his or her connection to the ground (such as through the feet, due to the voltage gradient in the earth, as discussed above), can cause great damage.
Telephones, modems, computers and other electronic devices can be damaged by lightning, as harmful overcurrent can reach them through the phone jack, Ethernet cable, or electricity outlet. A secondary effect of lightning on users of telephone equipment can be hearing damage, as the strike may cause bursts of extremely loud noise. Close strikes can also generate electromagnetic pulses (EMPs) – especially during ‘positive’ lightning discharges.
A green tree which was struck by lightning
A eucalyptus tree that was struck by lightning but two pine trees next to the tree are untouched, Darwin, Northern Territory, Australia.
Trees are frequent conductors of lightning to the ground. Since sap is a poor conductor, its electrical resistance causes it to be heated explosively into steam, which blows off the bark outside the lightning’s path. In following seasons trees overgrow the damaged area and may cover it completely, leaving only a vertical scar. If the damage is severe, the tree may not be able to recover, and decay sets in, eventually killing the tree. In sparsely populated areas such as the Russian Far East and Siberia, lightning strikes are one of the major causes of forest fires. The smoke and mist expelled by a forest fire can cause electric charges, multiplying the intensity of a forest fire. It is commonly thought that a tree standing alone is more frequently struck, though in some forested areas, lightning scars can be seen on almost every tree.
The two most frequently struck tree types are the oak and the elm. Pine trees are also quite often hit by lightning. Unlike the oak, which has a relatively shallow root structure, pine trees have a deep central root system that goes down into the water table. Pine trees usually stand taller than other species, which also makes them a likely target. Factors which lead to its being targeted are a high resin content, loftiness, and its needles which lend themselves to a high electrical discharge during a thunderstorm.
Trees are natural lightning conductors and are known to provide protection against lightning damage to nearby buildings. Tall trees with high biomass for the root system provide good lightning protection. An example is the teak tree (Tectona grandis). When planted near a building, its height helps to capture the oncoming lightning leader, and the high biomass of the root system helps in dissipation of the lightnings charge.
Lightning currents have a very fast risetime, on the order of 40 kA per microsecond. Hence, conductors of such currents exhibit marked skin effect, causing most of the currents to flow through the conductor skin.
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