Hurricanes develope from pre-existing tropical disturbance. Rina formed from a tropical disturbance that was situated between Nicaragua and Jamaica. As the graph below shows this area was experiencing high cloud heights, heavy rain and strong convection. Convection was stimulated by a low pressure center that forced the warm air high into the atmosphere.
Cloud height and Rainfall measurements.
As the pressure dropped the tropical disturbance was intensified and began to form a tropical storm. As the storm churned in the Caribean Sea it made its way toward Mexico's Yucatan peninsula. While it migrated it picked up the speed and momentum from the warm, moist air coditions provided by the Caribbean ocean surface. These are the conditions that fuel hurricanes and allow for stronger faster convection currents and lower pressure cells. The graph below illustrates how much the storm intesified when compared with the previouse graph.
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| Cloud Height/Rainfall |
By October 25th the tropical storm had become a category 2 hurricane. Warm air was forced higher into the atmosphere causing more unstable conditions and violent thunderstorms that surrounded the eye of the storm. Enormous Thunderheads grew high into the atmosphere from the intensifying uplifts of warm air that began to circulate in a counterclockwise rotation from the coriolis effect.
Infrared image of Hurricane Irene
Purple are stong thunder storms surrounding the center of the Hurricane.
Hurricanes thrive in warm moist conditions. Unstable air is associated with low pressure cells because it has a tendency to rise. As warm air rises it condenses. If it rises high enough it can reach its point of saturation. In the case of Hurricane Rina, the air rose so quickly that it cause large cumulonimbus clouds towering high in the troposphere, causing extreme thunderstorms and an ideal condition for a hurricane to form.
Fortunately by the time she made it to Mexico's eastcoast, the Category 2 hurricane had been downgraded back to a tropical storm. Wind shear, changing direction of the wind, slowed the momentum of her circulation. Once it came into contact with the peninsula the storm continued to weaken. When Rina began to move over the land mass it experienced drag and lack of moisture that the ocean provided and the fuel Rina needed to survive.
Unfortunately many out of towners vacations were cut short and cruise ships were re-routed to the east to avoid Rina. Although the hurricane weakend to a tropical storm by the time it hit Mexico it still brought with it extreme winds, high rain fall, high tides, and storm surges that caused flooding and damage to the peninsula.
