Learn how to tell the distance between a lightning strike and thunder.
Did you know that you can easily figure out how far you are from a lightning strike by watching the lightning flash and listening to thunder? Thunder and lightning actually happen at the same time, but since light travels faster than sound, you’ll see the light from lightning ahead of the grumbling sound of thunder.
The roar of thunder is caused by the rapidly expanding atmosphere when a bolt of lightning heats the air along its path. The time between the lightning flashes and thunder will tell you how far you are from the point where the lightning struck.
The Lightning 30/30 Rule
The lightning 30/30 rule is a great way to tell how far lightning struck and take precautionary measures to avoid falling victim to lightning strikes. If it takes less than 30 seconds to hear the roaring sound of thunder after seeing the flash of light, the lightning storm is close enough to pose a danger. So, after the storm ends, you should wait for at least 30 minutes before reengaging in outdoor activities.
How to Determine Distance between Thunder and Lightning
Thunder can be heard from a distance of approximately 10 miles from the point of the lightning strike. If you can hear the sound of thunder, it’s a warning that you’re within striking distance of the storm. When lightning strikes, the air temperature in the lightning path can soar as high as 50,000 degrees Fahrenheit (more than five times hotter than the sun’s surface).
Immediately after the flash, the surrounding air cools and contracts quickly, creating the sound wave referred to as thunder. Although lightning strikes will just hit one spot on the ground, it will travel several miles through the air. Typically, a sharp click or crack is an indication that the lightning channel passed close by. If you hear the sound of a rumble, lightning is at least several miles away.
To calculate the lightning thunder distance, you need to understand the difference between the speed of sound and light. It typically takes the sound of thunder 5 seconds to travel a mile. So, by counting the number of seconds it takes between the flash of lightning and the sound of thunder, you can determine how far you are from the lightning strike. Simply count the number of seconds between the flash and the sound of thunder and divide by 5 to get the distance in miles. So, 1 second = less than a mile (a fifth of a mile), 5 seconds = 1 mile, 20 seconds = 4 miles, etc.
This technique is known as the “flash-to-bang” method. It can keep you safe from lightning strikes during rainy summer weather. If the time between the lightning flash and the sound of thunder is less than 30 seconds, the National Weather Service recommends taking cover for at least 30 minutes. This is an indication that the lightning is less than 6 miles away and the next strike could potentially affect you.
How to Protect your Property from Lightning Strikes
Other than understanding the lightning thunder distance, you need to take proactive steps in protecting your property from lightning strikes. Lightning protection systems are customized to protect buildings and a multitude of other industrial facilities from direct and indirect lightning strikes. Typical lightning protection solutions are comprised of structural lightning protection, bonding and grounding, and surge protection.
Contact Lightning Master for Lightning Protection Services and Equipment
Since a direct or nearby lightning strike can cause extensive damage, we recommend working with a professional lightning protection company to safeguard your employees and property. At Lightning Master Corporation, we understand the science behind lightning strikes and will provide superior lightning protection products, services, and advice to mitigate risks associated with lightning storms. We also provide lightning protection for oil and gas, communication towers, tank batteries, and chemical plants. Contact us today at 727-447-6800 or [emailprotected] to schedule a no-cost consultation for lightning protection services.
FAQs
If you count the number of seconds between the flash of lightning and the sound of thunder, and then divide by 5, you'll get the distance in miles to the lightning: 5 seconds = 1 mile, 15 seconds = 3 miles, 0 seconds = very close. Keep in mind that you should be in a safe place while counting.
How can you determine the distance of lightning during a thunderstorm? ›
Just count the number of seconds that pass between a flash of lightning and the crack of thunder that follows it, then divide that number by five.
How can the distance of a lightning strike be determined if a lightning detector is not available? ›
You can tell how far away a lightning stroke is by counting the seconds between seeing the lightning flash and hearing the thunder. Five (5) seconds approximates one (1) mile of distance. If you see a flash and instantly hear the thunder, the lightning stroke was very close. Take shelter immediately.
How far away is lightning 10 seconds? ›
When you see the flash of a lightning bolt, you can start counting seconds and then divide to see how far away the lightning struck. If it takes 10 seconds for the thunder to roll in, the lightning struck about 2 miles or 3 kilometers away.
When the distance between the thunder and the lightning is less than how many seconds it means that you are in danger? ›
When You See Lightning, Count The Time Until You Hear Thunder. If That Is 30 Seconds Or Less, The Thunderstorm Is Close Enough To Be Dangerous – Seek Shelter (if you can't see the lightning, just hearing the thunder is a good back-up rule). Wait 30 Minutes Or More After The Lightning Flash Before Leaving Shelter.
How do you calculate distance? ›
You calculate distance traveled by using the formula d=rt. You will need to know the rate at which you are traveling and the total time you traveled. You can then multiply these two numbers together to determine the distance traveled.
What is the 30 30 rule for lightning? ›
Remember the 30/30 lightning safety rule: Go indoors if, after seeing lightning, you cannot count to 30 before hearing thunder. Stay indoors 30 minutes after hearing the last clap of thunder.
What is the method to determine distance of lightning? ›
If you count the number of seconds between the flash of lightning and the sound of thunder, and then divide by 5, you'll get the distance in miles to the lightning: 5 seconds = 1 mile, 15 seconds = 3 miles, 0 seconds = very close. Keep in mind that you should be in a safe place while counting.
What is the best lightning detection system for golf courses? ›
Thor Guard stands as the most effective predictor of lighting within a defined area of risk on the market. Through countless hours of monitoring, Thor Guard has been able to develop a proprietary program that reads activity within an electrostatic field.
Which comes first thunder or lightning? ›
In nature, a lightning flash and the associated thunder occur at almost the same time in a thunderstorm. A person on the ground sees the lightning flash before hearing the thunder because light at a speed of around 300,000,000 meters per second travels much faster than sound which moves at 340 meters per second.
As little kids, you probably were told to count the seconds between lightning and thunder so you'd know how many miles away lightning would be. "People get it wrong all the time," Van Voorhees said. Lightning's actually closer than you think because you must account for the speed of light, which is faster than sound.
Can there be thunder without lightning? ›
No, it is not possible to have thunder without lightning. Thunder starts as a shockwave from the explosively expanding lightning channel when a large current causes rapid heating. However, it is possible that you might see lightning and not hear the thunder because it was too far away.
What can protect you from lightning? ›
Fully enclosed buildings with wiring and plumbing are best. A hard-topped metal vehicle with the windows closed is also safe. Stay inside until 30 minutes after the last rumble of thunder. Sheds, picnic shelters, tents or covered porches do NOT protect you from lightning.
How many volts of electricity are in a lightning bolt? ›
Weather.gov > Safety > How Powerful Is Lightning? A typical lightning flash is about 300 million Volts and about 30,000 Amps. In comparison, household current is 120 Volts and 15 Amps.
How do you calculate light distance? ›
Since speed of light is represented by the variable “c”, you can rewrite the equation as d = c x t, where d is the distance of a light year, c is the speed of light and t is time. If you want to know the distance of a light year in kilometers, you will need to find the speed of light in kilometers per second.
How do you calculate the nearest point of lightning? ›
→ The distance of the nearest point of lightning = speed × time =346ms−1×2s=692m.
What is the radius of lightning detection? ›
An ALDF automatically detects more than 90% of all cloud-to-ground lightning occurring within a range of 100 km. Other lightning, such as cloud-to-cloud and intracloud lightning, is ignored. The National Lightning Detection Network (NLDN) is a network of more than 130 of these ALDF sensors.
How far away should lightning be? ›
In general, a significant lightning threat extends outward from the base of a thunderstorm cloud about 6 to 10 miles. It's important to account for the time it will take for everyone to get to safety. Here are some criteria that could be used to stop activities.
