Lightning

Utah Lightning Statistics by Month, Year and County (by the NWS)

General Information About Lightning

Each year, hundreds of Americans are hit by lightning, resulting in dozens of deaths and injuries. In fact, lightning causes more deaths per year in the United States than those from tornadoes or hurricanes.

Average U.S. Deaths Per Year 
(Based on 30-Year Normals)

Floods Lightning Tornadoes Hurricanes

140 90 80 30

In addition, lightning sparks thousands of fires and causes millions of dollars in damage to homes and businesses each year in the United States.

In Utah, lightning is the number one killer among weather phenomena:

Utah Deaths From Weather Phenomena
(January 1950 - August 2003)

Lightning 57
Flash Floods 26
Tornadoes 1

Briefly described, lightning is a massive electrical discharge, caused by the flow of electrons between oppositely charged parts of a cumulonimbus (thunderstorm) cloud or between the cloud and the ground. It's formed when clouds become electrically polarized--with a net positive charge near the top of the cloud and net negative charge in the lower part of the cloud. Exactly how this polarization occurs is still a mystery. However, a number of researchers suggest that a channel of electrons--called a stepped leader--sometimes flows out a cloud and moves towards the ground. The approach of this leader increases the ground's positive charge and draws a similar stream of positively charged electrons--called a pilot streamer--upwards. When the leader and streamer meet, a closed circuit is created and electrical current begins to flow. Electrons are discharged onto the ground and an upward moving return stroke heats the air and makes lightning visible.

Lightning is very powerful. It can discharge millions of volts of electricity, propel return strokes at nearly the speed of light, and heat surrounding air up to thousands of degrees Fahrenheit. When this superheated air explodes away from the electrical current it creates a shock wave called "thunder."

Lightning is extremely dangerous, highly unpredictable and very fickle. It can strike and destroy one object without touching another one nearby; or it can hit an object and travel across the ground for dozens of feet electrocuting anything in its path.

Here are five interesting facts about the affect of lightning on people and objects:

In 1991, lightning killed 73 people in the United States with five times as many males as females killed by lightning. The 10-39 age group tended to be the most susceptible to the dangers of lightning with 62% of the fatalities falling into that range. Also, 21 people perished standing under a tree, 12 died out in the open, and 10 in a boat.

Lightning does strike the same place twice. The Empire State Building in New York City is struck on the average of about 23 times per year.

On September 1, 1939, lightning hit and killed 835 sheep on the top of Pine Canyon in the Raft River Mountains of Box Elder County, Utah.

On June 28, 1956, a lightning bolt struck the top of a home in Cedar City, Utah, leaving a 10-foot wide hole in the roof.

On May 30, 1987, a giant coal truck (having tires seven feet tall) was hit by lightning at a strip mine near Providence, Kentucky. The six-wheel, 177,000 pound truck "felt like it had been picked up and set down, and shook all over." One of the six $4,000 steel-belted tires was blown from the rim and landed 30 feet away, another was turned inside out and a third went flat, leaving only one of the four rear tires intact. (Contrary to popular belief, the "rubber tires" of a car or truck do NOT protect people from lightning. Instead, the metal covering of the vehicle usually protects the occupants by conducting the electrical discharge across the vehicle and down into the ground.)

Lightning Safety Rules

Lightning normally strikes the tallest object in an area, and is particularly attracted to metal and objects near or on water. In other words, lightning loves three things: height, metal and water. Also history has shown that lightning's most likely targets are tall, isolated structures that are close to water, such as hilltops, swimming pools and lakes. These safety rules will help save your life:

• If inside a building or a metal-enclosed vehicle, remain inside.
• Inside a home, avoid using telephones and electrical appliances.
• If outside, seek cover in a large enclosed building or metal-enclosed vehicle.
• If outside and there is not time to reach a large enclosed building or metal-enclosed vehicle, follow these rules: 
  
  • Do not stand underneath a natural lightning rod such as an isolated tree (move away from any tree a distance that is twice the height of the tree).
  • Avoid projecting above the surrounding landscape as you would if you were standing on a hilltop, in an open field, on a beach, or fishing in a small, open boat.
  • Get out of and away from open water.
  • Get away from metallic equipment.
  • Get off of and away from motorcycles, scooters, golf carts, bicycles, and tractors without enclosed cabs.
  • Put down golf clubs.
  • Stay away from wire fences, clotheslines, metal pipes, metal rails, and other metallic conductors that can carry lightning to you from some distance away.
  • Avoid seeking shelter in small, isolated sheds or other structures in open areas.
  • If in a forest, seek shelter in a low area under a thick growth of small trees.
  • In open areas, go to a low place such as a ravine or gully, but be alert for flash floods.
  • If you are isolated in a level, open area and you feel your hair stand on end (indicating that lightning is about to strike), drop to your knees and bend forward putting your hands on your knees and your chin to you chest. Do NOT lie flat on the ground.

Much of the information for this section originally appeared in the copyrighted book Utah's Weather and Climate, edited by Dan Pope and Clayton Brough, in 1996. UCCW Directors have received permission from the copyright owners of this book to reproduce such information on its website and to revise and updated it where appropriate.