Wind patterns for the most part remain consistent throughout most of the
Caribbean. Some of these wind
patterns are caused by Land/Sea diurnal flows. During the day, the ocean is at a lower temperature (higher
pressure) than the land, which is at a higher temperature (lower pressure). Since
air always flows from high pressure to low pressure, winds during the day will
blow inland. This heated air will then
rise, cool and descend. This process will
continue during daylight hours and once it becomes night, the process is
reversed and winds will flow from land out to sea.
The predominate type of winds found throughout the tropics
are called trade winds. These
winds blow from the northeast in the northern hemisphere and from the southeast
in the southern hemisphere. During
hurricane season, these winds are the steering force that guide these
devastating storms. These winds
can also carry dust from Africa across the Atlantic Ocean and into the
Caribbean.
Trade winds also have an effect on the weather patterns of
the islands. The windward sides of
the islands tend to receive more moisture through precipitation. However, the leeward sides tend to be
drier.
The convergence of the northeast trade winds of the northern
hemisphere and the southeast trade winds of the southern hemisphere create the
Intertropical Convergence Zone.
This area of global air convergence forms a low pressure belt that spans
the equator. The air in this zone of low pressure is extremely moisture rich and
unstable. This leads to frequent precipitation throughout this region and explains why the
tropics have so much annual rainfall.
Hurricanes and tropical storms are common in the BVI's. The high sea surface
temperatures, the few changes in wind speed, the abundance of water vapor, along with
the convergence of trade winds all make for ideal conditions for powerful
storms to be produced.
