12 became Hurricane Katrina in Aug. 2005
Week continues with "Hurricane Force", an all new documentary offering
the definitive look at one of the most powerful forces of nature.
Cooks in the
kitchen follow recipes with specific ingredients and steps to achieve
culinary success. Leave out an important ingredient or miss a key step,
and the meal won't be great.
The atmosphere has a lot of variety on its menu. Cooking up a hurricane
is the result of following a particular recipe with the following
sea-surface temperatures, usually greater than 80°F
Weak vertical wind shear
(small changes in wind speed & direction with height) in the
and unstable atmosphere
distance away from the equator (so the earth's rotation can
help add some spin to the atmosphere)
Does that sound about right? Did we forget anything?
Go back into the kitchen for a moment. If you have all the right
ingredients, mix them all together in just the right amounts, and just
let them sit there, the meal won't just cook itself. You have to ignite
the burner to start the cooking.
What does this have to do with the atmosphere making hurricanes? Think
of this another way.
If you want to leave town fast, what do you do? Choose an interstate
with no traffic, make sure there's gas in the car, then drive, right?
Wait. There's an important thing in there you do, almost without
thinking about it. You have to start the car.
The atmosphere is the same way. Even with all the hurricane-making
ingredients on the list above, there will be no hurricane if the burner
isn't ignited - or if the car isn't started - to begin with.
Hurricane formation requires an initiating weather disturbance,
something with a little spin to spark the beginnings of development.
Hurricanes don't just magically appear over the fuel of warm waters
where there's no impediment from strong vertical wind shear.
So let's take a look at some of the trouble-making weather disturbances
that get the spin going, starting with the most prolific of all
Atlantic hurricane-makers: African easterly waves, or just tropical
waves for short...