When the atmospheric pressure in an offshore area is lower than its surroundings it produces an area under the influence of a low pressure weather system.
The low pressure cells + strong winds + atmospheric lift result in cyclonic storms.
Tropical or ‘equatorial cyclones’ are so named due to their origin being largely in the Tropics.
Formation is characteristically in moist (maritime) and warm (tropical) air masses. The process of rising moist (maritime) air produces heat that gives rise to condensation of the water vapour in the moist air. This in turn generates tropical cyclones. Such storms are characterized by thunderstorms that produce strong winds and flooding.