Anatomy

Since the advent of satellite imagery, we have had a chance to see hurricanes as distinct, swirling weather systems that blossom and advance on coastal areas during the summer and autumn months.  Moreover, the ability to see them coming, literally from space, allows people to be far more prepared than they were even 50 years ago. 

However, the greatest advances in understanding how hurricanes function have come from reconnaissance aircraft that risk life and limb to actually fly into the middle of these monsters and drop sounding equipment through the central “eye.” 

All weather is, from a scientific point of view, the interaction between energy and water, causing heat to be gained or lost within the closed system that is the Earth’s atmosphere, taken as whole.  Hurricanes are the result of a great deal of energy, in the form of heat, heating up water.  They always form over water.  Water is very good at storing energy and it feeds water vapour back up into the atmosphere, which is an even better conductor of energy – the system feeds upon itself to become larger until it goes over land or cold water.  It may also cross the path of low pressure going the other direction, disrupting the eddy and disorganizing the storm.

The early-season hurricanes that menace Florida usually (but not always) travel west across the Atlantic, from water heated up off the western coast of Africa and travelling north and west.  Atlantic hurricanes may also come from super heated water in the relatively shallow Gulf of Mexico coming north and east, particularly later in the season. 

Hurricanes are identifiable as being roughly circular and always turning counter-clockwise in the Northern Hemisphere.  Those in the Indian ocean are called typhoons while those in the southern hemisphere are called cyclones and spin clockwise – they’re all the exact same thing, though. 

A defining characteristic of large hurricanes is the eye.  In this zone of relative calm and very low atmospheric pressures, you may even be able to see right through to the ground as the skies below open up into brilliant sunlight for as long as a few hours.  The larger a hurricane becomes, the more energetic it becomes, organizing into the more distinctive doughnut-shape seen today on satellite pictures.  The area of greatest danger to life and property is where the eye makes “landfall.”

The eye forms because of convection currents that build up within the storm.  Hot air moves up and cold air moves down.  When this process is taken to an extreme, shearing winds are created that form bands in the storm itself and a column in the middle, where the winds are the strongest on the very edges.  This “eye wall” is like a tube of the most concentrated storm activity, including tornadoes and thunderstorms.

Tropical storms are not nearly as organized and really have only the potential to become a serious threat.  Even if a good-sized tropical depression or tropical storm hits a coastal area, it can contain enough rain to be a problem on already saturated ground, causing flooding. 

Hurricanes cause damage to the landscape and property with high winds, tornados, flooding and storm surges.  These surges have been known to cost the most lives and can be over 18 feet high in the case of a storm rated category 5 on the Saffir-Simpson scale.  Even a relatively small category 2 storm can cause an 8 foot surge wave to come crashing into beachfront property.

In the United States, the National Oceanic and Atmospheric Administration (NOAA) sets the names for storms on a rotating schedule and in alphabetical order.  The Atlantic and Pacific storm names alternate between starting with a boy’s or a girl’s name each year.  Since 1979, when storms cause a great loss of life or massive damage, their names are retired for at least 10 years.  As the 2005 season demonstrated, when the season goes beyond 26 letters, the Greek alphabet is used.

From your vantage point on the ground, it is always best to remain below until the “all-clear” is given.  Venturing outside when the eye is passing can be deadly.  Evacuating areas that are likely to be inundated by a storm surge is essential to avoid getting caught in what could be a life-threatening flood. 

The largest storms can deliver winds in excess of 155 miles an hour.  This is enough to remove windows, doors and small structures as well as completely covering anything up to 15 feet high as far as a quarter-mile inland.  Even much smaller storms, when they hit directly, can destroy mobile homes and uproot large trees.  A category 1 hurricane will have winds of at least 74 miles per hour.

The Saffir-Simpson Hurricane Intensity Scale Explained

One of the most cost-effective methods of saving lives during the Florida hurricane season is the use of the Saffir-Simpson hurricane scale.  It is known well enough in hurricane prone regions that the intensity of an oncoming storm can be quickly and easily understood by the majority of people with a simple rating on a 1-5 scale.

Initially developed for use by the United Nations, engineer Herbert Saffir, the idea was quickly picked up for use by the National Hurricane Centre by its then director Bob Simpson.  By 1969, researchers at the National Hurricane Center had come up with the definition of the scale that is still used today.

Generally, the scale describes the intensity of a hurricane by any number of factors that seem to directly correlate with the amount of damage seen on the ground, not the damage itself, as is the case with earthquakes.  The items measured are pressure at the center of the storm as measured in millibars (mb) of mercury, the winds as measured in knots and the height of the storm surge.

The scale applies to hurricanes only, though the National Oceanic and Aeronautic Administration (NOAA) also classifies tropical storms and tropical depressions according to the same scale guidelines.  When a storm reaches Tropical Storm status, with winds of 39-73mph, it is given a name. 

Hurricane names are taken from an alphabetical list that’s generated each year, alternating with boy’s and girl’s names.  Hurricanes that do particular damage or cause a major loss of life are retired from the list rotation for at least a decade.

NOAA and most international relief organizations consider storms that are rated at category-3 or higher to be “major,” though even smaller storms can cause significant flood and wind damage, especially in less developed nations that have deforestation problems.  Similar scales are used in other countries for hurricanes and typhoons in the northern hemisphere as well as cyclones in the southern hemisphere, since they’re all the same thing, anyhow.

The damage from a category-3 storm is usually characterized as being extensive.  Instead of the normal roughly 1000mb of pressure, the center of such a storm will have pressure between 945 and 964mb, with winds sustained for at least 1 minute at 111-130 mph (or 96-113 knots) as measured 30 feet above the surface.  The surge from a category-3 hurricane may be as high as 12 feet – high enough to reach some second story apartments.  Such storms can remove all the foliage from trees, completely destroy mobile homes and do structural damage to smaller site-built structures.

Mobile or manufactured homes are especially vulnerable to hurricane damage.  Because of this, the federal government (which funds all flood insurance) has mandated that all mobile homes must be able to withstand 100 mph winds without major structural damage since the early 1990s.  However, anyone living in a mobile homes built before then will want to seek immediate shelter elsewhere if even a category-2 storm is on the way.

Category-5 storms are so strong that a direct hit from such a storm is almost guaranteed to severely damage even the strongest structures with winds in excess of 155 mph and expected storm surges of more than 18 feet.  It is not uncommon to see entire houses blown apart or toppled over in such a hurricane.  Of course, damage varies widely over the entire area affected by the hurricane, with the greatest damage occurring immediately before and after the “eye-wall” of greatest intensity makes landfall. Fortunately, because of the tremendous amount of energy required to sustain a category-5 storm, such storms usually decrease in intensity by the time they make landfall.

Nevertheless, even a category-3 or category-4 storm can cause significant damage and loss of life, even well into the interior of the state. Just because you do not live in a coastal county, you should not assume that a hurricane cannot significantly affect you. Ask anyone in land-locked Polk County, Florida, which was hit by three hurricanes in 2004, and they will assure you that living inland is no guarantee against major hurricane damage.

Agricultural Hurricane Damage and its Impact on the Florida Economy

Florida produces a majority of the citrus for culinary and juice production in North America.  It is also home to the nation’s leading supply of houseplants and semi-tropical nursery stock as well as a major share of high value edible horticulture such as tomatoes and sweet corn.  Cattle and other grazing animals are also very commonly found in Florida, accounting for millions of dollars worth of livestock.  A hurricane can wipe out an entire crop, just as it’s being harvested, uproot trees and cause a worldwide increase in the price of certain commodity crops.  Florida’s agricultural bounty is greater than most countries and therefore, has far-reaching implications.

When Hurricane Charley hit in 2004, the more than 280 crops commercially grown in the state that experienced some sort of damage represented the second largest element of Florida’s economy, right behind tourism.  With agricultural damages alone in the billions, the nearly 100,000 people employed by the industry were temporarily out of work when they needed it the most.  Of the 44,000 full-time farmers and ranchers in the state, a few hundred were forced out as a result of that storm alone. 

Even the best crop insurance may not be enough to get citrus farmers or ranchers back on their feet again.  While those who grow herbaceous crops such as tomato or tobacco farmers can bounce back with the next season, those who ranch or grow tree fruits are looking at several years without a crop. 

Even 3-year-old citrus trees (most are planted as 1-year “whips” to save money) planted in a hurricane-devastated grove will take as long as a decade to reach full productivity.  While dwarfing rootstocks can decrease that time to 6 or 7 years, such orchards will have to be planted at a far higher density than a standard grove, requiring a greater number of more expensive plants than the crop insurance is likely to cover.

Those in the ranching industry will have at least an 18-month wait before they see any money back. 

The impact on Florida’s economy ripples out from those who own or work on farms to the state as a whole in what eventually becomes real human issues, related to economic factors.  Rural communities that depend on the spending power of those farm owners and farm workers can be decimated, again, at precisely the wrong time, as those incomes move out of the small town to look for work in the big city. Nearby cities feel the pressure of an influx of workers who have job skills that are of little use in an urban area.

Those who are not directly involved will feel the pinch at the market.  The price of usually affordable fresh fruits and vegetables (or orange juice) will certainly increase.  Even if crops can be shipped in from elsewhere, they will certainly have the expense of “food miles” associated with them.  If the storm comes from the Gulf of Mexico and the price of fuel jumps with an interruption in refining capacity, the price will jump that much higher. 

Hurricane Andrew -- The Turning Point for Florida Homeowners

On August 21, 1992, five days after it formed off the coast of Africa, Tropical Storm Andrew seemed to be losing steam.  Still churning far out into the Atlantic, it made a surprise turn into very warm waters that had very little wind aloft.  In just 48 hours it intensified into a monster that packed sustained winds of over 165mph and in eye pressure of about 922mb when it smacked into the South Florida coast.  While not the largest or strongest hurricane ever seen in the Atlantic, it would become the costliest natural disaster ($45 billion in 2005 dollars) ever in the United States until Hurricane Katrina in September of 2005 and change the history of south Florida forever.

It is somewhat rare for a hurricane to make landfall as a Category-5 storm.  These are defined as hurricanes with sustained winds (for at least 1 minute at a height of 30 feet above the surface) in excess of 155 mph and pacing a storm surge of over 18 feet.  Andrew was the last of only three storms to do so in the entire 20^th century.  Because of the relatively high cost of life, with 65 related casualties (most of them in Florida), the name has been officially and permanently retired. 

Andrew made landfall at Homestead, Florida, though a great deal of the monetary damage resulted from the devastation of Miami and greater Dade County.  Entire neighbourhoods were flattened.  It is estimated that 90% of the roofs in Dade County sustained major damage.  Water had to be boiled for weeks afterwards and the Keys went without any station-generated electric power for months.

Looting ensued, and hundreds of National Guard troops were called in to restore the peace, though aid was still several days away.  Homestead Air Force Base was all but destroyed in the action and was shut down as an active duty base, all its personal sent to Italy instead.

As a result of the billions of dollars paid out by private insurance companies, 11 insurance companies went out of business, with another 20 having their funds so severely depleted they were forced to leave the Florida property insurance market completely. More than one million homes were made uninsurable as a result and were subsequently covered by the precursor to today’s Citizens Insurance or demolished as a total loss.

Thankfully, the containment reactor of the Turkey Point Nuclear Reactor was the only part of the plant not destroyed in Andrew’s direct hit.  Unlike the rest of the state, it was built to withstand 235mph winds, such as those that can be generated in a particularly strong tornado.

The ultimate effect of this disaster was the nearly complete restructuring of the insurance industry in Florida and an exodus of new construction in more northerly counties when insurance was no longer available to the south.  The Florida Hurricane Catastrophe Fund and the precursors to Citizens were created as a result.  Other efforts to keep insurers in the state included the practices of percentage deductibles and allowing insurers to use catastrophe models when calculating premiums and overall risk. 

While premiums across the state jumped considerably after the 1992 hurricane season, they skyrocketed again as a result of the 2004 and 2005 seasons that resulted in nearly $30 billion in new claims.  Not only are rates for homeowners, hurricane, sinkhole and flood insurance in Florida among the highest in the nation (by far), but auto, home and life insurance premiums are also higher as a result of companies that want to make their money back anyway they can.