Arizona Lightning

It can happen between a cloud and the ground, between clouds, and even from one part of a cloud to another part.

Cloud-to-ground lightning forms when rising air currents in a thunderstorm cause lots of collisions between ice particles.

All that colliding results in the separation of positively and negatively charged particles, creating huge electrical charge differences.

The negatively-charged particles drop to the middle and lower parts of the storm.

The traveling thunderstorm also gathers positively charged particles along the ground that move within the storm.

As the difference in charges between the particles increases, the positive particles rise up, the negative particles travel downward and an invisible electrical channel of energy develops.

Arizona lightning briefly lights up the city. Photo: iStockphoto

The electrical transfer in this channel is the lightning that we see.

As the air is heated by the channel, it rapidly expands, causing the shock wave we hear as thunder.

If you hear a sharp, loud "crack," you just heard a bolt hit the ground.

Storm chasers know that southern Arizona is an excellent place to watch for stikes. Why?

Because the air is generally clear and the cloud bases are often very high.

How can you tell how far away that strike was?

Here’s a simple rule: When you see the flash, count the number of seconds until you hear thunder and divide by 5.

This will tell you how many miles you are from the strike.

A thunderstorm moves over Monument Valley on the Navajo Nation. Photo: iStockphoto

Essentially this equates to 1 mile for every 5 seconds - more or less the speed of sound (761 miles per hour).

Thunderstorms are generally several miles in diameter and lightning can originate from any part of the storm.

There is no way to predict where and when it will strike.

• Remember to Follow the 30/30 Rule: if less than 30 seconds pass between the time you see a flash of light and hear the first roll of thunder, immediately seek shelter in the nearest building. Lightning is less than 6 miles away from you. Remain inside for at least 30 minutes after you see the last flash of light and hear the last sound of thunder.




• If you can’t see any flashes of light but are hearing thunder, lightning is within striking range of you.




• Do not wait for rain before finding shelter as you can be struck even if no rain is present.




• If no building is available, seek shelter in a metal-topped vehicle. Roll up the windows. Lean away from the door. Put your hands in your lap and keep your hands and feet off any metal parts, the steering wheel, gear shift, etc.

There’s a widely held myth that a car will protect you because the rubber tires ground the charge.

Unfortunately that’s not true. You can still be hit if you’re in a vehicle.

However, if you only option for shelter is the vehicle or being outside, get in the car. Electricity travels around the metal frame to the ground, providing some, though not foolproof, protection.

Indoor Safety

• Stay off the phone unless it is an emergency. Electrical discharges can travel over the line to you.




• Stay away from plumbing fixtures, appliances, water sources, windows and doors and metal objects.




• Do not shower or bathe during thunderstorms.




• Never touch wiring during a thunderstorm.




• Turn off all unnecessary electrical equipment.




• Unplug sensitive electronic equipment before a thunderstorm arrives. If you count 30 seconds or less between the light flash and the sound of thunder, it’s too late to unplug without risking injury to yourself.

• Arizona ranks number 23 in lightning frequency in the lower 48 states.




• There is lightning risk even if it is not raining where you are. Strikes can happen outside the rain area in thunderstorms. This is especially true in southern Arizona, which often has dry thunderstorms that produce strikes with no rain.




• A bolt can strike in the same place twice.




• Most strikes occur during the afternoon or early evening. Late afternoon is the deadliest period.




• Fatalities and injuries tend to occur more often at the end of a storm than at any other times; least often in the middle of storms.




• The Federal Emergency Management Agency (FEMA) estimates there are 200 deaths and 750 severe injuries from cloud-to-ground lightning annually in the United States.




• According to the National Weather Service, your chance of being struck by lightning in the United States in your lifetime is 1 in 3,000.




• 9 out of 10 people struck survive, though they frequently suffer lifelong, debilitating symptoms such as memory loss, dizziness, weakness, muscle spasms and depression.




• The United States gets about 25 million cloud-to-ground strikes every year.




• One bolt strikes the ground for every three flashes you see in the clouds.




• The most common locations to be struck are open fields or under trees.




• The distance between successive flashes can be anywhere from 2 to 6 miles apart.




• Lightning can travel 60 miles or more, often extending up to 10 miles away from the cloud that formed it. Generally, however, a bolt travels 10 miles or less.




• A bolt is about 1-inch in diameter.




• The temperature of lightning peaks around 50,000 degrees Fahrenheit - 5 times hotter than the surface of the sun.

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