You might be thinking that thunderstorms only happen in the summer when the weather is hot, but that is not the case. Thunderstorms occur when warm air lies under colder air in an unstable atmosphere.

The warm air will rise quickly and condense into water droplets to form a cumulonimbus cloud. Within the cloud, the warm air and water droplets continue to rise and will eventually freeze into positively charged ice crystals. When the ice crystals are heavy enough, they begin to fall as hail.

As the hail falls, it becomes negatively charged. The negatively charged pieces of hail at the base of the cloud then become attracted to the positively charged Earth's surface.

When the attraction is strong enough, the charges come together, creating a flash of lightning. It is the rapid expansion and heating of the air that causes the claps of thunder.

You can see if there are any thunderstorms occurring on the WeatherRadar anywhere in the world. Just look for the yellow dots (lightning) inside the blue color (rain).