Lightning - The Big Strike

The summer thunderstorm season is upon us and it might be helpful to take a look at lightning and understand some of the ways we can protect ourselves.

Lightning is one of nature’s most awesome displays and one of its more dangerous, and most misunderstood. We are in the middle of summer, traditionally the time of powerful thunderstorms that boom and crack and pour, and are gone in a few minutes. Behind they leave cracked and downed trees, power outages and sometimes injured bystanders.

Lightning has a long history with mankind… think of the metaphors usually associated with speed, and the use of lightning bolts as symbols of power.

Let’s take a look at lightning and see what it is about. Lightning is electricity… not exactly what you get when you flip on the light switch, but more like the kind you get when you shuffle across the carpet and touch the doorknob, but hugely amplified. It is estimated that a lightning bolt operates at many millions of volts, and generates temperatures of several thousand degrees. Scientists, including electrical engineers, and meteorologists are not in total agreement on what lightning is, but seem to agree that inside the huge upwelling clouds that typically occur late on a hot summer day, there are very strong currents that move water droplets, dust particles and ice particles rapidly up and down. This process causes the droplets and particles to become either positively or negatively charged, and the clouds will end up with a huge voltage differential between the top and bottom. The charge at the bottom of the cloud, a few hundred metres from the ground, will try to neutralise its charge to the nearest ground, and that will typically be a tall building, an antenna or a tree.

What happens then is a small “leader”, a relatively weak discharge, tracks upward from the ground to the cloud, and the really big strike follows the path created by the leader to the ground. The big flash, the burned and split tree, and the noisy crack then follow.

The rumble of thunder is caused by the bolt superheating a channel of air that surrounds it. The closer the flash and the boom, the closer the actual bolt is to you. One mile per five seconds of delay is the general rule.

Not all lightning is cloud-to-ground; there is what is called “heat lightning” or “sheet lightning” which is cloud-to-cloud discharge, as well as discharges within the same cloud.

The damage caused by lightning can vary greatly. We hear of many cattle being killed by a single strike, yet people have survived strikes with little more than some minor burns. Huge trees may be split from top to bottom, others lose a few branches. A chain may be fused into a single piece, and a fine necklace may leave only a small burn mark.

The old wives’ tale about lightning never striking twice is just that – an old wives tale. The Empire State Building in New York City is struck about 25 times per year. One unlucky park ranger in the US has been struck seven times, and is still around to talk about it!


According to Environment Canada, lightning kills about six Canadians per year and injures about 75, as well as causing numerous forest fires. Windsor seems to be the “Lightning Capital of Canada”, with up to 250 strikes per year in the city. Ottawa records about 90.

There are a number of things you can do to protect yourself in the event you or your group are caught in a storm where there may be lightning. The first thing is to have a plan as to where to shelter, and assign someone to monitor the weather and report any approaching storm. Under a tree is not a good place to seek shelter, but inside a sturdy building, an automobile or bus is generally safe. Open vehicles such as a golf cart or an ATV are not safe, as it is the steel bodywork that protects you. Do not use a telephone, the water taps, and turn off the TV. If you are caught outside, try to find a low-lying area such as a ditch or hollow. You’ll be wet but safe. Crouch down, and if you are part of a group, separate yourselves. Make sure you remove your I-Pod and any earphones you are wearing, and turn off your cell phone. There is no evidence to suggest that I-Pods or cell phones “attract” lightning, but wiring and metallic objects can act as a pathway. Stay well away from steel fences and antennas. Golfers should not wave their 9-iron angrily in the air, and most courses will call golfers in if a lightning storm is approaching.

One interesting product of lightning strikes is something called a fulgurite (fulgur is the Latin word for lightning). A fulgurite is a tube of fused and melted sand formed by the heat of a lightning strike, and it looks like a gnarled branch, varying in length from a few centimetres to several metres, with a coloured glassy interior. They are typically found on beaches and in deserts. In what has got to be one of the world’s worst jobs, people in Florida pound steel rods into the sand at the beach when a lightning storm is approaching, then hope for a strike which will form a fulgurite, which can then be dug up and sold.

Lightning is one of Nature’s most dramatic displays, but you can lessen your danger by using a few simple steps and some common sense to protect yourself.