Environmental Geology
Hurricanes/Tropical Cyclones
These are called many things including hurricanes in the
Hurricanes are an example of a runaway thermal convection in the atmosphere.
Develop in maritime tropical air masses dominated by convection and not by weather fronts, in contrast to the severe storms we looked at that were associated with frontal lifting.
A hurricane is a huge, migratory, circular, low pressure storm with winds greater than 74 mph.
They form due to massive and rapid uplift of warm moist air
Hurricanes form over tropical oceans with sea surface temperatures greater than 80 degrees F.
Average diameter is about 100 – 300 miles
Height includes the entire troposphere
Life Cycle
Components:
Atlantic Hurricanes form as an energy output along the west
coast of
Then travels west in the easterly trade winds with a small vector to the north.
Eventually, these storms curve poleward and are then transported into the westerlies
They lose energy rapidly when they make landfall and the warm ocean energy source is cut off or when they move out over colder waters.
Life span from the time it reaches tropical storm status is typically 3 to 5 days.
Seasonality:
Fall peak: lags the summers solstice due to thermal inertia of the ocean. Peak of the season is September 11.
Stafir-Simpson Scale – based on damage potential
Category 1-5 with 1 being least damaging and 5 being the most damaging.
Number of hurricanes by category that made landfall along
the
Category 1 - 60
Category 2 – 41
Category 3 – 49
Category 4 – 15
Category 5 - 2