Hurricanes - What are Hurricanes How do they work also names for the 2013 Hurricane season and more

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Hurricane: What are Hurricanes, How do they work and 2013 Hurricane Names

What are Hurricanes and How do they work?

The Atlantic hurricane season is "officially" from June 1st to November 30th, but most hurricanes form from August through October with peak activity in early to mid September. As Ralph Waldo Emerson observed nature can at times be very contrary. The best we can do is to learn the ins and outs of Hurricanes and be prepared. So... here goes. What Are Hurricanes?, What should we do when a Hurricane Warning is issued?

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"What are hurricanes"?

Simple Answer: Hurricanes are tropical cyclones with winds that exceed 64 knots (74 mi/hr) and rotate counterclockwise abo
The Atlantic hurricane season is "officially" from June 1st to November 30th, but most hurricanes form from August through October with peak activity in early to mid September. As Ralph Waldo Emerson observed nature can at times be very contrary. The best we can do is to learn the ins and outs of Hurricanes and be prepared. So... here goes. What Are Hurricanes?, What should we do when a Hurricane Warning is issued?

personalities. Even television weatherman and women, sometimes perpetuate that feeling with phrases like : "Hurricane so-and-so has turned and now has her eyes set on our town" . Well hurricanes don't have eyes, they have a single eye and it is not used to look for unsuspecting towns to ravage. Hurricanes are among the most powerful climatic events to occur on our planet. Fortunately Hurricanes are relatively slow to develop and can be fairly well forecast with modern computer modeling techniques.

Lets look at some of the truths and dynamics of Hurricanes.

Hurricane eye: A region typically 20-50 km in diameter found at the center of a hurricane where skies are often clear and winds are light. The storm's lowest pressure readings are found here. Eye wall is a wall of clouds and intense thunderstorms that surround the eye. Spiral rainbands: bands of thunderstorms that wrap around the hurricane. Where and when do hurricanes form? Hurricanes are born over tropical oceans where there are warm waters, humid air and converging winds. Red areas on map above are seasonably favorable for the development of Hurricanes, Cyclones or Typhoons. The hurricane season normally runs from June 1st through November 30th , when the water temperature in these regions is relatively high (greater than 27 C).

Average number of tropical storms in each year

There are an average of 85 tropical storms and 45 hurricanes/Typhoons globally per year; and about nine named storms form per year in the tropical Atlantic and Gulf of Mexico area, with around six of those becoming hurricanes and two of those becoming intense hurricanes (those with sustained winds exceeding 130 mph or 209 km/hr).

Getting The Name Right. Hurricanes are called by different names in the different regions of the world.

Development of a Hurricane the organized convection theory

When a cold air mass is located above an organized cluster of tropical thunderstorms, and unstable atmosphere results. This instability leads to the development of convection.
Fueled by convection, strong vertical updrafts (red arrows) lift air and moisture upwards, favoring the development of large cumulonimbus clouds.
The air exits at the top of the cloud and begins to sink back downward (blue arrows).

Hurricane Stages of Development. Hurricanes go through a set of stages from birth to dissipation.

Tropical disturbance is the beginning of a hurricane, and it has no strong winds or closed isobars around an area of low pressure containing cloudiness and some precipitation. Tropical disturbances commonly exist in the tropical trade winds at any one time.

Tropical depression is the next stage of a developing hurricane. It has at least one closed isobar that accompanies a drop in pressure in the center of the storm. As the surface pressure begins to fall and the winds increase to between 20 and 34 knots the tropical disturbances become tropical depressions.

Tropical storm is stronger than a depression as the central pressure drops, resulting in several closed isobars at the surface. Surface winds increase to speeds of 35 and 64 knots. The storm becomes more organized and the appearance begins to resemble a hurricane because of the intensifying circulation around the center of the storm.

As surface pressures continue to drop, strengthening the pressure gradient of the storm, the storm becomes a hurricane when sustained wind speeds exceed 64 knots. The storm takes on the familiar hurricane appearance. A pronounced rotation develops around the central core. The eye develops corresponding to the lowest atmospheric pressure near the center of the storm with spiral rain bands rotating around the eye of the storm.

2013 Hurricane Names

Alberto	Beryl	Chris
Debby	Ernesto	Florence
Gordon	Helene	Isaac
Joyce	Kirk	Leslie
Michael	Nadine	Oscar
Patty	Rafael	Sandy
Tony	Valerie	William

Movement of Hurricanes

Hurricane movement is strongly related to the global winds.

The easterly winds in the tropics usually steer hurricanes westward. Most storms then gradually swing north-westward around the subtropical high to the north. If the storm moves into middle latitudes, the prevailing westerlies steer it northeastward.
The typical paths of hurricanes are shown in the diagram below. The typical hurricane originating in the northern hemisphere moves toward the west with bending northward and then northeastward as it moves into more higher latitudes.

As a result, the Gulf and East Coast of the United States are at greater risk to experience one or more hurricanes each year.
Day to day course changes in a storm are partly affected by upper level winds, water temperature, the relative proximity of high pressure systems and other low pressure areas.
The result is meteorologist can now feed the the location and predicted movement of these upper level winds, high and low pressure systems, water temps and more into a computer with Hurricane modeling software.

This software will predict the influence these systems might have on the storm. You might think that they would then be able to predict the future course of the storm, but we are not that far yet.
The National Hurricane Center has multiple software programs designed by different developers. The data is entered into all of them, then the results are compared. Ideally forecasters would like to see all of the models agree on the influence global weather will have on the Hurricane, when the models disagree the forecasters have to look at averages and use there own experience to predict the future track and strength of a hurricane.

Because hurricanes derive their energy from the warm surface water and from the latent heat of condensation, they tend to dissipate rapidly when they move over cold water or over a large mass of land.
There are several destructive components of hurricanes in addition to the high winds.

Flooding

Is a common occurrence with hurricanes. Heavy rains and ocean waters brought ashore by strong winds can result in flooding exceeding 50 cm (20 in) over a 24 hour period. The runoff systems in many cities cannot handle such an increase in water because of the gentle topography in many of the coastal areas where hurricanes occured.

Storm surge

Is an abnormal increase in the ocean's level, sometimes in excess of several meters high and miles wide. Storm surges can come ashore up to five hours before the storm and destroy low elevation coastal areas, and consequently, is responsible for most hurricane related deaths. It is especially damaging when the storm surge occurs during high tide.

Tornadoes

May also develop in hurricanes. A number theories exist about their origin, but in the case of Hurricane Andrew, severe damage was inflicted by small Spin-Up Vortices that developed in regions of strong wind-shear found in the hurricane's the eye wall. The strong damaging winds of the hurricane frequently cover the smaller tornado paths making the separation of their damaging effects very difficult.