This document last updated on 06-Nov-2014 EENS 3050 Natural Disasters

Thunderstorms occur anywhere that warm moist air has absorbed enough heat to make the air less dense than the surrounding air. This commonly occurs along cold fronts, but can occur in other places as well, particularly where daytime heating forms hot air near the Earth's surface. As the warm moist air rises it begins to cool and water begins to condense into tiny droplets that form clouds. Condensation of the water droplets in the clouds releases the latent heat of evaporation, adding heat to the rising air, thus decreasing its density and allowing it to rise to higher levels in the atmosphere. This rising air, called an updraft, starts to build clouds to heights of up to 6 km. Further rising and cooling within the clouds causes more condensation, as well as the formation of ice crystals which release further latent heat and build cloud heights up to 12 km. Eventually the water droplets and ice crystals in the clouds become so large that they can no longer be supported by the uprising air mass, and they begin to fall forming rapid downdrafts on the leading edge of the cloud. In the mature stage of thunderstorm development updrafts an