Here we have two pictures of hurricane Fran, taken on September 5, 1996. Hurricanes form in the summer and fall when intense low pressure systems form over the ocean. As the air moves in towards the low pressure zone, the Coriolis force due to the rotation of the earth causes the air to move in a counterclockwise direction (in the Northern hemisphere). The spiralling motion over a warm sea increases the moisture and energy content, and the storm builds up over time. Once the hurricane moves inland, it loses its power source and quickly dissipates, but not before causing great damage.