Silent lightning explained - and whether it's dangerous (2024)

Many people have observed "silent lightning", otherwise known as "heat lightning" during the summer storms this heatwave

As temperatures soar to record-breaking highs across the UK, the heatwave is triggering a number of impressive summer storms.

Many people have taken to social media to express their confusion over the weather phenomenon of "silent lightning" that has been occurring recently.

But what is causing this strange, seemingly thunder-less lightning, and is it dangerous?

What is silent lightning?

A lightning strike is an electric charge from the atmosphere, that normally produces a violent crack or slow, low grumble.

Silent lightning, otherwise known as heat lightning, is when lightning occurs but is not followed by the expected roll of thunder.

When lightning is silent it is likely that it comes from a distant thunderstorm that is too far away for people to hear any noise.

Nicola Maxey, for the Met Office, said: "It's not an unusual phenomenon. Light travels further than sound.

"You sometimes see the lightning flash but you are too far away to hear the thunder.”

How close do you have to be to lightning to hear thunder?

The number of seconds between a flash of lightning and the rumble of thunder can tell you how close you are to the storm.

For every five seconds between the light and the noise, which travels slower, you are approximately one mile away.

It is generally said that if the thunder occurs less than 30 seconds after you see the flash, it is close enough to pose a threat.

The sound of thunder can normally only be heard for about 10 miles from a flash, where as the flash can be seen from further.

Often mountains, hills, trees or the curvature of the earth prevent an observer from seeing the actual lightning flash, instead they just see the light being reflected off higher-level clouds.

Is it dangerous?

Silent lightning is not out of the ordinary, but still poses the same safety concerns as any storm.

People should take care during a storm, and should remain safely inside wherever possible.

The risk of being struck by lightning is very low, but can be fatal or cause severe injuries.