What causes thunder and lightning?
Thunderstorms with thunder and lightning occur mainly (but not exclusively!) in warm weather when the atmosphere is unstable and cumulonimbus clouds form. They occur when warm air at ground level rises and collides with cooler air above it.
Lightning is an electrical discharge that occurs between clouds, travelling from the cloud to the air or from the cloud to the ground, while thunder occurs due to the rapid heating of the air by lightning.
How dangerous is a thunderstorm?
The amperage in a lightning discharge reaches 20,000 to 30,000 amperes. This is about 2,300 times the electricity used by a washing machine.
According to the Royal Society for the Prevention of Accidents, between 30 and 60 people are struck by lightning each year in the UK alone, and around three cases (5-10 per cent) are fatal. People who spend a lot of time outdoors in unprotected areas are most at risk.
It’s not just a direct hit from a discharge that is to be feared. Any lightning strike near a person can be dangerous.
How far away is a thunderstorm?
To find out the distance to the storm, you need to count the number of seconds between the lightning strike and the thunder. According to rough calculations, every 3 seconds can be equated to a kilometre, i.e. if there are 6 seconds between lightning and thunder, the storm is very close – about two kilometres away.
If the time between the lightning flash and the thunder strike is 30 seconds or less, you should seek shelter.
In the event of an impending thunderstorm, you should:
1. Switch off all electrical appliances, including the television, as lightning can cause power surges.
2. While indoors, avoid using a landline phone, as phone lines can conduct electricity. It is also best to avoid using taps and sinks with metal pipes as they can also conduct electricity.
3 If you are outdoors, try to stay about 20 metres away from all metal objects (poles, billboards, etc.). If possible, take shelter indoors.
