Analysing the sound of thunderstorms

Weatherwatch: Meteorologists are counting 'thunder days' - and checking they're not hearing jet planes or fireworks

Rumbles of thunder have been performing multiple symphonies in the skies recently. Already the UK has clocked up more than its average quota of thunderstorms for a whole year. Normally, the most thunder-prone region - London and the south-east - would expect to have 15 to 19 days when thunder is heard, but by mid-June that number had already been exceeded. However, recognising the sound of thunder isn't always easy.

For more than 100 years, meteorologists across the UK have noted the days on which they hear a rumble of thunder. These "thunder days" make an invaluable contribution to understanding global warming and changes in the weather. But sometimes observers can be conned into thinking they heard thunder, when in fact the rumble was a jet plane passing over, or a firework exploding.