Thursday, August 11, 2011
Health Care and Lightning Strikes
According to Intellicast.com, lightning is an atmospheric discharge of electricity, which typically occurs during thunderstorms, and sometimes during volcanic eruptions or dust storms. In the atmospheric electrical discharge, a leader of a bolt of lightning can travel at speeds of 60,000 m/s, and can reach temperatures approaching 30,000°C (54,000°F), hot enough to fuse soil or sand into glass channels. There are over 16 million lightning storms every year. Lightning can also occur within the ash clouds from volcanic eruptions, or can be caused by violent forest fires which generate sufficient dust to create a static charge.
Here are a few quick lightning facts from NOAA Weather Service:
--25 million cloud-to-ground lightning strikes occur in the United States each year.
--Lightning can heat its path five times hotter than the surface of the sun.
--One ground lightning stroke can generate between 100 million and 1 billion volts of electricity.
--Each year, an average of 73 people are killed and 300 injured by lightning strikes in the US.
How lightning initially forms is still a matter of debate: Scientists have studied root causes ranging from atmospheric perturbations (wind, humidity, and atmospheric pressure) to the impact of solar wind and accumulation of charged solar particles. Ice inside a cloud is thought to be a key element in lightning development, and may cause a forcible separation of positive and negative charges within the cloud, thus assisting in the formation of lightning, according to Intellicast.
When the first strike occurs, current flows in an attempt to neutralize the charge separation, according to the website HowStuffWorks.com. This requires that the current associated with the energy in the other step leaders also flows to the ground. The electrons in the other step leaders, being free to move, flow through the leader to the strike path. So when the strike occurs, the other step leaders are providing current and exhibiting the same heat flash characteristics of the actual strike path. After the original stroke occurs, it is usually followed by a series of secondary strikes. These strikes follow only the path of the main strike; the other step leaders do not participate in this discharge.
In nature, what you see is often not what you get, and this is definitely the case with the secondary strikes. It is very possible that the main strike can be followed by 30 to 40 secondary strikes. Depending on the time delay between the strikes, you may see what looks like one long-duration main strike, or a main strike followed by other flashes along the path of the main strike. These conditions are easy to understand if you realize that the secondary strike can occur while the flash from the main stroke is still visible. Obviously, this would cause a viewer to think that the main-stroke flash lasted longer than it actually did. By the same token, the secondary strikes may occur after the flash from the main strike ends, making it appear that the main strike is flickering.
According to How Stuff Works, there are several types of lightning:
•Normal lightning - Discussed previously.
•Sheet lightning - Normal lightning that is reflected in the clouds.
•Heat lightning - Normal lightning near the horizon that is reflected by high clouds.
•Ball lightning - A phenomenon where lightning forms a slow, moving ball that can burn objects in its path before exploding or burning out.
•Red sprite - A red burst reported to occur above storm clouds and reaching a few miles in length (toward the stratosphere).
•Blue jet - A blue, cone-shaped burst that occurs above the center of a storm cloud and moves upward (toward the stratosphere) at a high rate of speed.
According to NOAA's National Weather Service, you should be aware of the warning signs for lightning strikes. High winds, rainfall, and a darkening cloud cover are the warning signs for possible cloud-to-ground lightning strikes. While many lightning casualties happen at the beginning of an approaching storm, more than 50 percent of lightning deaths occur after the thunderstorm has passed. The lightning threat diminishes after the last sound of thunder, but may persist for more than 30 minutes. When thunderstorms are in the area, but not overhead, the lightning threat can exist when skies are clear.
NOAA suggests following strict safety precautions for lightning. While nothing offers absolute safety from lightning, some actions can greatly reduce your risks. If a storm is approaching, avoid being in, or near, high places, open fields, isolated trees, unprotected gazebos, rain or picnic shelters, baseball dugouts, communications towers, flagpoles, light poles, bleachers (metal or wood), metal fences, convertibles, golf carts and water. If you can see lightning or hear thunder, the risk is already present. Louder or more frequent thunder means lightning activity is approaching, increasing the risk for lightning injury or death. If the time delay between seeing the lightning and hearing the thunder is less than 30 seconds, you are in danger.
No place is absolutely safe from the lightning threat, however, some places are safer than others. Large enclosed structures are safer than smaller, or open, structures. Avoiding lightning injury inside a building depends on whether the structure incorporates lightning protection and its size. When inside during a thunderstorm, avoid using the telephone, taking a shower, washing your hands, doing dishes, or having contact with conductive surfaces, including metal doors, window frames, wiring and plumbing. Generally, enclosed metal vehicles, with the windows rolled up, provide good shelter from lightning.
Having an action plan for outside events is essential, especially if a thunderstorm approaches. Coordinators of outdoor events should monitor the weather and evacuate participants when appropriate. School buses are an excellent lightning shelter, which outdoor event organizers can provide. Consider placing lightning safety tips and/or the action plan in game programs, flyers, scorecards, etc., and placing lightning safety placards around the area. Lightning warning signs are effective means of communicating the lightning threat to the general public and raise awareness.
Ninety percent of lightning victims survive their encounter with lightning, especially with timely medical treatment. Individuals struck by lightning do not carry a charge, and it is safe to touch them and provide medical treatment. Call 911 and start mouth-to-mouth resuscitation. If the victim has no pulse, begin cardiac compressions. In cold, wet situations put a protective layer between the victim and the ground to lower the risk of hypothermia.
Lightning is dangerous, and should be treated with the utmost respect. It is deadly when ignored. Use common sense when faced with a thunderstorm, and consider the alternatives. Being safe is better than being dead from a lightning strike.
Until next time.