Lightning strike

[1][2] Lightning strikes the average commercial aircraft at least once a year, but modern engineering and design means this is rarely a problem.

[citation needed] Lightning strikes can injure humans in several different ways:[4][5] Warning signs of an impending strike nearby can include a crackling sound, sensations of static electricity in the hair or skin, the pungent smell of ozone, or the appearance of a blue haze around persons or objects (St. Elmo's fire).

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.

The relatively high voltage drop around poorer electrical conductors (such as a human being), causes the surrounding air to ionize and break down, and the external flashover diverts most of the main discharge current so that it passes "around" the body, reducing injury.

[10] During a flash, though, the current flowing through the channel and around the body can generate large electromagnetic fields and EMPs, which may induce electrical transients (surges) within the nervous system or pacemaker of the heart, upsetting normal operations.

This effect might explain cases where cardiac arrest or seizures followed a lightning strike that produced no external injuries.

According to the National Oceanic and Atmospheric Administration in 2012, over the twenty years to 2012 the United States averaged 51 annual lightning strike fatalities, making it the second-most frequent cause of weather-related death after floods.

Kisii's high rate of lightning fatalities occurs because of the frequency of thunderstorms and because many of the area's structures have metal roofs.

[22] These statistics do not reflect the difference between direct strikes, where the victim was part of the lightning pathway, indirect effects of being close to the termination point, such as ground currents, and resultant, where the casualty arose from subsequent events, such as fires or explosions.

Even the most knowledgeable first responders may not recognize a lightning-related injury, let alone particulars, which a medical examiner, police investigator, or on the rare occasion a trained lightning expert may have difficulty identifying to record accurately.

[27] Since sap is a relatively poor conductor, its electrical resistance causes it to be heated explosively into steam, which blows off the bark outside the lightning's path.

In sparsely populated areas such as the Russian Far East and Siberia, lightning strikes are one of the major causes of forest fires.

[29][30] 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.

The field of lightning-protection systems is an enormous industry worldwide due to the impacts lightning can have on the constructs and activities of humankind.

Lightning, as varied in properties measured across orders of magnitude as it is, can cause direct effects or have secondary impacts; lead to the complete destruction of a facility or process or simply cause the failure of a remote electronic sensor; it can result in outdoor activities being halted for safety concerns to employees as a thunderstorm nears an area and until it has sufficiently passed; it can ignite volatile commodities stored in large quantities or interfere with the normal operation of a piece of equipment at critical periods of time.

However, products and systems have been designed of varying complexities to alert people as the probability of a strike increases above a set level determined by a risk assessment for the location's conditions and circumstances.

The strikes and atmospheric flashes are not predicted, but the level of detail recorded by these technologies has vastly improved in the past 20 years.

Lightning-detection systems have been developed and may be deployed in locations where lightning strikes present special risks, such as public parks.

Such systems are designed to detect the conditions which are believed to favor lightning strikes and provide a warning to those in the vicinity to allow them to take appropriate cover.

[38] A person injured by lightning does not carry an electrical charge, and can be safely handled to apply first aid before emergency services arrive.

A research team from the University of Colombo found that even in neighborhoods that had experienced deaths from lightning, no precautions were taken against future storms.

[40] Safety measures All events associated or suspected of causing damage are called "lightning incidents" due to four important factors.