Lightning: Electrically fascinating, but don’t underestimate its deadly impact

The Weather Authority
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By definition, any rainstorm is considered a thunderstorm if thunder can be heard. And if thunder is rolling, then that means lightning is present -- and it could strike you if you are not careful.

Lightning 101: How it forms

Lightning is a spark of electrical current flowing from the cloud to the ground, or even from one cloud to another. The atmospheric form of lightning is a giant version of the static electricity "shock" you experience when you rub your feet on the carpet and then touch the door knob.

Electrical charges within a thundercloud. (Source: NOAA)
Electrical currents within a thundercloud. (Source: NOAA)

Within a thundercloud, rising and falling air currents (called updrafts and downdrafts) carry water and ice particles higher into the sky. These particles rub up on one another, causing particles to become positively charged (ie, losing an electron) or negatively charged (ie, gaining an electron).

Eventually the charged particles sift into different layers within the cloud, causing an electric differential to develop within the cloud. When enough oppositely charged particles build up within the cloud, electrons flow from the negatively charged part of the cloud to the positively charged part of the cloud.

Lightning is HOT, that's why it causes thunder

A bolt of lightning is so incredibly hot, it can heat the air around it to 18,000 degrees Fahrenheit!

This rapid heating -- followed by quick cooling -- of the air causes it rapidly expand and contract, which then creates a shockwave. That wave continues to travel through the air as a sound wave until it reaches your eardrums, which is what you hear as thunder. In order for thunder to occur, lightning must be present! If you can hear thunder, that is your cue that lightning is close enough to strike you.

If you hear thunder -- or see the flash of a lightning bolt -- immediately head indoors and remain inside until 30 minutes after the last flash or boom.

Lightning can strike as far as 10 miles from its cloud, known as a "bolt from the blue"

A lightning bolt emanates from the top of a cumulonimbus cloud to an area of the ground free fro rain. This is an example of a "bolt from the blue" and illustrates how lightning can strike as far as 10 miles from its parent cloud. (Source: National Weather Service/Al Moller)
A lightning bolt emanates from the top of a cumulonimbus cloud to an area of the ground free fro rain. This is an example of a "bolt from the blue" and illustrates how lightning can strike as far as 10 miles from its parent cloud. (Source: National Weather Service/Al Moller)

One of the most dangerous types of lightning to occur is the "bolt from the blue".

Often, in the spring and summertime, a thunderstorm can develop as far as 10 miles away from a given point.

Anyone enjoying outdoor activities at that point may only see sunshine, and they may not necessarily notice the towering thunderstorm developing a few miles down the road, mainly due to elevation changes or even obscurity due to trees and buildings, etc.

However, as the electrical charges build inside the thunderstorm, enough positive charges may build within the top of the cloud to solicit electrons from the ground as far as 10 miles away. As a result, lightning can strike, even though the thundercloud was hidden -- the result is a "bolt from the clear blue sky".

This is why you should always head indoors if you can hear thunder, even if all you see is sunshine. Thunderstorms can move very quickly, so lightning may be approaching before you even know it. Research shows that "bolts from the blue" can travel more than 25 miles away from the "parent" thundercloud.

Lightning safety: What you need to know so that you don't get struck

Since 2006, as many as 20 to 50 people are struck and killed by lightning strikes. With that said, only 10 percent of people struck by lighting are killed; the remaining 90 percent are left with varying degrees of injury, according to the Lightning Injury Research Program.

Lightning strike survivors often experience short-term injuries like superficial burns where the electricity enters and leaves the body; intense headaches; ringing in the ears; concussions; dizziness; nausea or vomiting; as well as potentially life-long injuries to the brain/nervous system.

There are five ways that lightning can strike a person:

    • 1.) Direct strike (person becomes a part of the main lightning channel on its way from the cloud to the ground)
Example of a direct lightning strike.
1.) Example of a direct lightning strike.
    • 2.) Side flash (lightning jumps from an object like a tree or pole to a person standing nearby)
2.) Example of how lightning can strike a tree, with a side flash striking a person nearby.
    • 3.) Ground current (as lightning flows into the ground, some of it may reach the person and flow through them before it disperses)
3.) Example of how lightning's current can strike someone from below the ground.
3.)Close up example of how electrons flow through a body in contact with an electrical current.
    • 4.) Conduction (the electrical current travels through conducting materials like metal fences, electrical wiring, plumbing, etc)
4.) Example of how conduction allows lightning to travel from a tree to a fence and injure someone in contact with the fence.
  • 5.) Streamers (electrons flowing from the ground into and through the person its way up to the sky to meet with a lightning bolt)
5.) Example of how streamers can electrically injure a person.

So how can you avoid putting yourself in danger of being struck by lightning?

Women inside a Faraday Cage at the Discovery Palace in Paris (Credit: Antoine Taveneaux)
Women inside a Faraday Cage at the Discovery Palace in Paris (Credit: Antoine Taveneaux)
  • Most importantly, when thunder roars, go indoors. For those who are deaf or hard of hearing, if you see a flash, dash inside. There is no safe spot to be outside, so head indoors immediately. Find a building that has substantial plumbing or electrical wiring, since those features will direct the flow of a potential lightning strike away from you to the ground.
  • If a building is not available, get inside a vehicle that is not a convertible or soft top. Contrary to popular belief, it is not the rubber tires that protects you, but rather the hollow metal cage that makes up the body of the car (the faraday cage effect) 
  • If you are on or near a body of water (ie, the beach, river or lake) and you see a flash of lightning or hear a rumble of thunder, head to shore immediately and seek shelter. The majority (37 percent) of lightning-related deaths occur during water activities, with 48 percent of those succumbing to lightning did so while fishing.
  • If you are inside, you are not 100 percent safe from lightning. Avoid using electronics like computers, phones, and gaming systems unless they are wireless. Avoid using anything that requires being near plumbing like kitchen or bathroom sinks. Avoid sitting near a window since lightning can move through the glass and strike anyone sitting nearby.

Our Live Alert 19 app will notify you if lightning has been detected in the area. It is free for both Apple and Android devices, and you can program it for different locations, including if you are at the beach or relaxing on the lake.


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