As rising water vapor condenses and latent heat is released, surrounding air is warmed and made less dense, causing the air to rise. The thunderstorms that make up the hurricane’s core are strengthened by this process. As air rises within the storms, pressure at the surface decreases and moister, tropical air is drawn to the center of the circulation, providing even more water vapor to fuel the hurricane. A hurricane has sustained wind gusts of at least 74 mph.