Can You Have Thunder Without Lightning?

by Jack Holt

With the recent thunder and lightning storms on the south coast, you may have wondered if you can have thunder without lightning. Despite common misconceptions, lightning and thunder are the same thing; besides that one is light and the other is sound. Thunder is just the sound produced from the rapid heating of the air around the lightning as millions of volts of electricity surge towards the earth in a fraction of a second. The air reaches temperatures higher than the surface of the sun, causing it to explode outwards producing an immense pressure gradient that is soon broken in the phenomenon named thunder. This disruption of pressure produces the sound waves that travel up to 10 miles to reach us. It is always heard after the strike because the light from the bolt reaches you before the sound waves of the thunder (lightning). 

Nearer to the actual lightning strike the frequency of the sound is much higher and is not yet absorbed by the surrounding air, resulting in a tearing sound. Slightly further from the strike the highest frequencies have been absorbed by the air and the sound is more of a loud crack. Much further away only the low frequencies caused by the immense pressure change can be detected, producing a rumbling noise we most clearly associate with thunder. If you can hear thunder you are within range of a lightning strike, these huge discharges can reach tens of miles in horizontal length so if the sound can reach you, so can the lightning. The odds of getting struck by lightning in your lifetime are approximately 1 in 16000, however there is only a 10% chance it is fatal. 

When a charge difference is present in a cloud (the process of producing lightning is far more complex than this) and a charge is earthing, roughly 100m from the surface, objects or ‘targets’ send up a spark that meets the charge and allows a huge electric current to flow down it and meet the spark, causing a lightning strike. Taller objects such as trees or buildings are more likely to cause the spark, therefore making them more likely ‘targets’. The best thing you can do if you hear thunder is to get indoors or, if without sufficient shelter, crouch down in an open area away from any trees or tall objects to avoid a lightning strike. 

So in conclusion, you cannot have thunder without lightning.