Tropical Storm Barry was a godsend for Florida, southern Georgia and the Southeast Coast, bringing 2-10 inches of rain to the area and putting a large dent in the regional drought. Hopefully, a few more of these tropical systems will bring an end to the wildfires and water shortages.
Like all Tropical Cyclones, Barry began as a Tropical Disturbance; this meteorological term refers to a cluster of thunderstorms that persists for 24 hours or more and moves with no relation to a front. In Barry's case, this distrubance developed in the western Caribbean while, later in the hurricane season, many develop as tropical waves, moving west from Africa. Once an internal rotation develops and sustained winds reach 23 miles per hour, the system becomes a Tropical Depression; Tropical Storms (which are named) have winds between 39 and 73 miles per hour while Hurricanes have sustained winds of 74 mph or higher.
The development of tropical storms requires three conditions: a water surface temperature of 80 degrees F or above, high local humidity and a lack of shearing winds in the upper atmosphere. As the thunderstorm cluster becomes organized, warm, humid air is drawn up through the center of the system, reinforcing the central low pressure and drawing in warm, humid air from the periphery. Condensation occurs in the upper levels of the storm, releasing energy which moves outward, enhancing the circulation and releasing the precipitation, which falls in heavy bands. If conditions remain favorable, this cycle continues, the storm intensifies and prodigious amounts of moisture are drawn into the atmosphere. Since the air is relatively warm at all levels, tropical systems produce far more rain than their northern cousins, the nor'easters.
