Storms are the most impressive of the everyday weather events and can cause lots of damage. They bring heavy rain, lightning, hail and sometimes tornadoes and waterspouts. During a thunderstorm the sky is dominated by towering cumulonimbus clouds. These can reach heights of up to 19 km (12 miles). High level winds sculpt the top of the cloud to an anvil. Inside each cloud, tremendous energy is generated and unleashed in the form of swirling upcurrents and spectacular bursts of high-voltage electricity.

Large amounts of heat energy are released as water vapour first condenses and then freezes inside the cloud. The heat energy creates powerful rising air currents that swirl upwards to the tropopause. Cool descending air currents produce strong downdraughts below the storm. After the storm has spent its energy, the rising currents die away and downdraughts break up the cloud. At any particular moment in time there are approximately 2,000 thunderstorms occurring in the Earth's atmosphere. A typical storm lasts about 1-2 hours. Individual stormclouds can measure 2-10 km across. Find out more about stormchasing, and how to protect yourself from severe weather.