Because the converging winds spiral inward toward the central low pressure area, the winds rotate in a clockwise direction around the central low in the southern hemisphere (counterclockwise in the northern hemisphere). As these winds spiral inward they draw in the thunderclouds around the storm, creating the spiral rain bands that are clearly visible on satellite images.
As the winds converge toward the central core, they spiral upwards, sending warm moist air upwards. As this air rises, it cools and releases its latent heat into the atmosphere to add further energy to the storm. The winds spiraling around this central core create the eye of the tropical cyclone and eventually spread out at high altitudes. Eventually, cool air above the eye begins to sink into the central core. This dry descending air within the eye gives the core a clear, cloud free sky, with little to no wind.
Since the main source of energy for the storm is the heat contained in the warm tropical and subtropical oceans, if the storm moves over the land, it is cut off from its source of heat and will rapidly dissipate.
spiraling counterclockwise (in the northern hemisphere) into the eye of the
hurricane achieve high velocities as they approach the low pressure of the
eye. The velocity of these winds is called the hurricane-wind velocity. The
central low pressure center of the eye also moves across the surface of the
Earth as it is pushed by regional winds. The velocity at which the eye moves
across the surface is called the storm center velocity. Thus, when we consider
the velocity of winds around the hurricane we must take into account both
the wind velocity and the storm center velocity. Depending on the side of
the hurricane, these velocities can either add or subtract. In the example
at the left, the hurricane is traveling north with a storm center velocity
of 30 km/hr, and a hurricane-wind velocity of 150 km/hr. On the right hand
side of the storm both velocities are to the north so the total wind velocity
is 180 km/hr (30 + 150). On the left hand side of the storm, however, the
wind is blowing to the south. Thus, since the storm is moving in the opposite
direction to the winds, the velocities subtract and the total wind velocity
is 120 km/hr (150 - 30). This is an important point. Winds are always stronger
on the right side of a moving hurricane in the northern hemisphere. The opposite
is true in the southern hemisphere, since winds circulate in a clockwise
direction, the winds are stronger on the left-hand side of the storm in the