Thunderstorms can be loud, sometimes frightening if one is right overhead, and occasionally prolonged with plenty of rain, thunder and lightning. Sometimes you only get one bolt of lightning or a diffuse flash, while at other times it seems as if they carry on forever, along with a distinct amount of thunder.
But what causes them? Any thunderstorm basically needs two things to develop. It needs lots of moisture in the air and it also needs warm air that is close to the ground. Think of a period of hot weather that has gone on for a few days and consider how the air feels. Chances are it can become muggy and sticky – not something a lot of us enjoy feeling. So these conditions are ideal for a thunderstorm to eventually develop. It’s hot close to the ground where we are, and it feels sticky because there is more moisture in the air.
You may also know the air temperature higher up is cooler than it is on the ground in these conditions. This is the classic situation that results in a thunderstorm with everything that usually goes with it.
The lightning can occur in two forms – sheet lightning or bolt lightning. Electrical fields can be generated in the dark clouds that typically alert us to the possibility of a thunderstorm. This triggers sparks. If the sparks stay in the clouds they’re known as sheet lightning. However they can come down to the earth and typically hit the first and easiest point they find.
As for the thunder, well, that is caused by the lightning. As the lightning occurs the air around it heats and cools very quickly, as you’d imagine. It is this process that causes the thunder to occur. The time between the two helps determine how far away the storm is compared to your location. While they occur together, we detect light sooner than we hear sound due to the time it takes them both to travel. This is why when they occur together it means the storm is right there overhead.
Once you understand the conditions under which a thunderstorm can occur, you can understand why they often happen after a period of hot dry weather. While it doesn’t always happen, the odds of experiencing a thunderstorm do become shorter after hot weather, especially when it feels muggy.
So the next time the temperatures rise and you enjoy several days of lovely weather, take a look at the skies from time to time. You may just realise the odds of a thunderstorm coming will get shorter the longer the weather goes on for. The good thing is if it is muggy, you’ll notice a drop in temperature when the thunderstorm finally comes to an end.