Lightning without thunder: Why lots of people didn't hear thunder claps during Tuesday night's storm; People in Wales were woken up by flashes of lighting and heavy rain.
Byline: Lydia Stephens
Wales was hit by a fierce thunderstorm on Tuesday night, but people have been questioning why they heard no thunder as the lightning struck.
Thestorm hit during the early hours of the morning,as predicted by the Met Office, who had previously issued a yellow weather warning.
And while you may have been woken up by flashing lights, for many it wasn't accompanied by the rumbling sound of thunder.
That is because you may not have been close enough to the lightning to hear the thunder clap, according tothe Met Office.
If you didn't hear any thunder last night, it's likely you were located more than 20km away from the lightning strike.
Atmospheric conditions also affect whether thunder can be heard or not, as the sound can be pushed up and away from the surface.
What causes thunder?
Thunder is essentially the sound produced by lightning. The intense heat caused by lightning causes the air to rapidly expand outward into the cooler air around it, creating a rippling shockwave.
That shockwave creates the rumbling clap of thunder. Thunder lasts longer than lightning because sound takes longer to travel than light.
The thunder clap can be heard as either a sudden, loud crack or a low, long rumble. The louder the thunder, the closer the lightning.
What causes lightning?
Lightning is a huge electrical discharge that flows between clouds, from a cloud to air, or from a cloud to the ground, according to the Met Office.
There are several different types of lightning such as ball, rocket, pearl-necklace, ribbon, forked, sheet and streak lightning.
Tiny water droplets form inside a storm cloud which are propelled to the top of the cloud and turn to ice.
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Some of these turn to hail and become to heavy so they fall back through the clould, bumping into smaller ice particles as they do so.
These collisions cause electrons to transfer to other hail in the cloud, giving it a negative charge, while the ice particles that have lost electrons gain a positive charge.
In the meantime, updraughts in the storm cloud continue to travel upwards, giving the top of the cloud a positive charge.
The hail, with the negative charge, travels to the bottom.
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"As well as being attracted to the positive charge in the top of the cloud, the surplus of electrons in the cloud base are attracted to positive charge in other clouds and on the ground," says the Met Office.
"If the attraction is strong enough, the electrons will rapidly move towards the positive atoms. The path they make in doing so forms the channel we see during a flash of lightning."
Credit: Howard Royce
Lightning over Cardiff bay
Credit: Elizabeth Scammell
The lightning over Cardiff last night
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|Publication:||Wales Online (Cardiff, Wales)|
|Date:||Jul 24, 2019|
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