Characteristics of Hurricanes: Structure, Types, Impact, History

Explore the characteristics of hurricanes, including their structure, nomenclature, types, rotation, dissipation, consequences, cyclonic waves, and some of the greatest hurricanes in history. Learn about the origin of the term “hurricane,” naming conventions, various types of hurricanes, the role of cyclonic waves, and notable historical storms like Hurricane Katrina, Maria, Harvey, the Great Galveston Hurricane, and Typhoon Haiyan.

Hurricanes are a type of tropical cyclones characterized by high intensity winds, thunderstorms and heavy and constant rainfall. They are characteristic of the northeast basin of the Pacific Ocean and that of the North Atlantic, where the Caribbean Sea and the Gulf of Mexico are included.

Hurricanes are natural disasters that are very common in the region, often resulting in significant human and material losses. Many of them, in fact, are preserved in popular memory because of how brutal they were.

However, hurricanes are always formed within a specific season, and outside of it they usually do not occur except in very specific cases. This allows foreseeing them and taking the pertinent measures to minimize their impact. To be considered properly a hurricane, any cyclone must present winds of at least 119 kilometers per hour.

Characteristics Of Hurricane

1. Origin

The term “hurricane” originates from the Caribbean word “huracán,” which was borrowed by Spanish colonizers from the indigenous Taíno people. The Taíno people used this term to refer to powerful storms, particularly those that occurred in the West Indies. When Spanish explorers encountered these storms in the Caribbean, they adopted the term “huracán” to describe these intense cyclonic weather events.

The modern word “hurricane” is used in the Atlantic and eastern Pacific Oceans to describe tropical cyclones with sustained winds of 74 miles per hour (119 kilometers per hour) or higher. These storms originate over warm tropical or subtropical waters, where the ocean’s heat and moisture provide the energy needed for their formation.

Hurricanes are known by different names in other parts of the world:

• In the northwestern Pacific, they are called “typhoons.”
• In the southwestern Pacific and Indian Ocean, they are known as “cyclones.”

Despite the different names, these storms are all essentially the same type of weather phenomenon: large rotating systems of clouds and thunderstorms that form over warm ocean waters.

The formation of a hurricane typically follows these steps:

1. Warm Ocean Waters: Hurricanes form over warm ocean waters, typically with temperatures of 80 degrees Fahrenheit (26.5 degrees Celsius) or higher. This warm water provides the heat and moisture needed to fuel the storm.
2. Low Pressure: A pre-existing weather disturbance, such as a tropical wave or a cluster of thunderstorms, can develop into a hurricane if conditions are right. As the warm, moist air over the ocean rises, it creates an area of low pressure.
3. Spin: The Coriolis effect, caused by the rotation of the Earth, causes the air to spin around the low-pressure center. This spin becomes the rotating system of clouds and thunderstorms characteristic of hurricanes.
4. Formation of the Eye: As the storm intensifies, an “eye” may form at the center. The eye is a region of calm, relatively clear weather surrounded by the eyewall, which contains the storm’s strongest winds and heaviest rainfall.
5. Mature Hurricane: If the storm continues to gather strength and organization, it becomes a mature hurricane with well-defined bands of clouds spiraling outward from the center.
6. Landfall or Dissipation: Hurricanes can either make landfall, bringing destructive winds, storm surges, and heavy rainfall to coastal areas, or they can dissipate as they move over cooler waters or encounter unfavorable atmospheric conditions.

The process of hurricane formation and intensification is complex and influenced by various factors such as sea surface temperatures, atmospheric stability, wind shear, and moisture content. Understanding the origin and development of hurricanes is crucial for forecasting and preparing for these powerful and potentially destructive storms.

2. Structure

Hurricanes are powerful tropical storms that form over warm ocean waters. They are characterized by several key features in their structure:

1. Eye: At the center of a hurricane is the eye, which is a relatively calm, clear area of low pressure. The eye is typically circular and can range from 20 to 40 miles in diameter, although it can be larger in some extremely intense storms. Skies are often clear in the eye, and winds are light or nearly calm. The eye is surrounded by the eyewall.
2. Eyewall: The eyewall is a ring of thunderstorms that surrounds the eye. This is where the most intense winds and rainfall occur in a hurricane. The eyewall is where the strongest updrafts are located, leading to the formation of intense rainbands and sometimes tornadoes.
3. Rainbands: These are bands of clouds and thunderstorms that spiral outward from the center of the storm. Rainbands are responsible for producing much of the rainfall associated with hurricanes. They can extend hundreds of miles from the center of the storm and often contain intense convective activity.
4. Spiral Bands: These are similar to rainbands but are more diffuse and less intense. They also spiral outward from the center of the storm and can bring periods of heavy rain and gusty winds.
5. Outflow: Hurricanes have a distinctive outflow pattern at their upper levels, where air flows outward from the center in a clockwise direction in the Northern Hemisphere (counterclockwise in the Southern Hemisphere). This outflow helps to ventilate the storm and maintain its strength.
6. Central Dense Overcast (CDO): This is a large mass of clouds and thunderstorms that covers the center of the storm. It is often associated with intense convection and is a sign of a healthy, developing hurricane.
7. Storm Surge: While not part of the physical structure, storm surge is a significant characteristic of hurricanes. It is a dome of water pushed ashore by the hurricane’s winds. Storm surge is often the most dangerous and damaging aspect of a hurricane, causing widespread flooding along the coast.

These characteristics combine to create the powerful and destructive nature of hurricanes, with their strong winds, heavy rainfall, and storm surge posing significant threats to life and property.

3. Nomenclature

The naming of hurricanes follows a system established by the World Meteorological Organization (WMO). There are separate lists of names for Atlantic hurricanes and Eastern Pacific hurricanes, with names chosen by regional weather agencies. Here are some key points about the nomenclature of hurricanes:

1. Lists of Names: The WMO maintains a set of rotating lists of names for hurricanes. Each list contains names that are used every six years. The lists alternate between male and female names. If a hurricane is particularly deadly or costly, its name may be retired from the list and replaced with a new name.
2. Atlantic Hurricane Names: The Atlantic hurricane season runs from June 1st to November 30th. For the Atlantic basin, there are six lists of names that rotate. So, the list used in one year will be used again six years later. If a storm is particularly damaging or deadly, its name is retired. For example, Hurricane Katrina, which devastated New Orleans in 2005, was retired from the list.
3. Eastern Pacific Hurricane Names: The Eastern Pacific hurricane season runs from May 15th to November 30th. The naming convention for Eastern Pacific storms is the same as for Atlantic storms, with lists of alternating male and female names.
4. Name Selection: Names for hurricanes are not chosen randomly. They are selected from lists of predetermined names that are chosen based on many factors, including regional languages, cultures, and the likelihood that the names will be easily recognizable and remembered.
5. Alphabetical Order: Hurricane names are assigned in alphabetical order throughout the season. So, the first storm of the year will have a name that starts with ‘A’, the second with ‘B’, and so on. However, not all letters of the alphabet are used, especially for less common letters like Q, U, X, Y, and Z.
6. Retirement: When a hurricane causes significant loss of life or damage, its name can be retired. This means it is removed from the list of names and replaced with another name beginning with the same letter. This is done to avoid confusion and show respect for those affected by the storm.
7. Use of Greek Alphabet: In very active hurricane seasons where the designated list of names is exhausted, the Greek alphabet has been used to name additional storms. This happened in the exceptionally active 2020 Atlantic hurricane season.
8. International Collaboration: The naming of hurricanes is an international effort. Various countries and regional meteorological agencies contribute to the naming lists, ensuring a diverse and culturally sensitive selection of names.

Overall, the naming of hurricanes serves practical purposes, such as facilitating communication and awareness during hurricane events. It also helps with historical record-keeping and public safety messaging.

4. Types of hurricane

Hurricanes, also known as cyclones or typhoons depending on their location, can be classified into different types based on their intensity and characteristics. Here are the main types:

1. Tropical Depression: This is the earliest stage of a tropical cyclone. It is characterized by a closed low-pressure circulation with maximum sustained winds of up to 38 miles per hour (62 kilometers per hour).
2. Tropical Storm: A tropical depression becomes a tropical storm when its maximum sustained winds reach 39 to 73 miles per hour (63 to 118 kilometers per hour). At this stage, the storm develops a more organized circulation and starts to form a clear center.
3. Hurricane/Cyclone/Typhoon (Category 1-5): Hurricanes are classified into different categories based on the Saffir-Simpson Hurricane Wind Scale (for Atlantic and eastern Pacific hurricanes) or similar scales (for other ocean basins). The categories are determined by the hurricane’s maximum sustained wind speed:
   • Category 1: Winds 74-95 mph (119-153 km/h) – Very dangerous winds will produce some damage.
   • Category 2: Winds 96-110 mph (154-177 km/h) – Extremely dangerous winds will cause extensive damage.
   • Category 3: Winds 111-129 mph (178-208 km/h) – Devastating damage will occur.
   • Category 4: Winds 130-156 mph (209-251 km/h) – Catastrophic damage will occur.
   • Category 5: Winds 157 mph or higher (252 km/h or higher) – Catastrophic damage will occur.

   These are the most intense hurricanes, capable of causing widespread destruction with their extremely strong winds, heavy rainfall, and storm surge.

4. Major Hurricane: This refers to hurricanes that are Category 3 or higher on the Saffir-Simpson scale. These storms are considered major due to their potential for significant damage and danger.
5. Medicane: A “medicane” is a Mediterranean tropical-like cyclone. These storms have some characteristics of tropical cyclones but form over the Mediterranean Sea, which is not usually warm enough to support traditional tropical cyclone development. Medicane is a portmanteau of “Mediterranean” and “hurricane.”
6. Subtropical Storm: These are hybrid systems that have some characteristics of both tropical and extratropical cyclones. They typically have a broader wind field and are less organized than tropical storms and hurricanes.
7. Extratropical Cyclone: While not technically a “hurricane,” these cyclones can evolve from hurricanes as they move over colder waters and transition into more typical mid-latitude weather systems. They can still produce strong winds and heavy rainfall but lack the characteristic eye and eyewall of a hurricane.

These classifications help meteorologists and emergency managers communicate the potential impacts of a storm and allow residents in affected areas to prepare accordingly.

5. Rotation

Hurricanes, also known as tropical cyclones or typhoons, are characterized by their rotation, which is a key feature of their structure and behavior. The rotation of a hurricane is influenced by the Coriolis effect, which is a result of the Earth’s rotation. Here are some key points about the rotation of hurricanes:

1. Coriolis Effect: As air moves toward the center of a low-pressure system, such as a hurricane, it is deflected by the Coriolis effect. In the Northern Hemisphere, this deflection causes the air to rotate counterclockwise around the center of the storm. In the Southern Hemisphere, it rotates clockwise. This rotation is known as cyclonic rotation.
2. Eye: At the center of a hurricane is the eye, which is a relatively calm area with light winds and often clear skies. The air in the eye descends, creating a region of low pressure. In strong hurricanes, the eye can have a diameter ranging from a few miles to over 20 miles (32 kilometers).
3. Eyewall: Surrounding the eye is the eyewall, where the strongest winds and heaviest rainfall are found. The eyewall is where the most intense convection and updrafts occur, leading to the formation of intense thunderstorms. The air in the eyewall rises and spirals inward toward the center of the storm.
4. Spiral Bands: Beyond the eyewall, spiral bands of thunderstorms extend outward from the center of the storm. These bands also rotate cyclonically and are responsible for producing additional rainfall and gusty winds.
5. Outflow: At the upper levels of the storm, air flows outward from the center in all directions. This outflow helps to maintain the storm’s circulation and can enhance its strength.
6. Storm Surge: While not directly related to rotation, the counterclockwise rotation of a hurricane in the Northern Hemisphere (or clockwise in the Southern Hemisphere) plays a role in generating storm surge. As the hurricane’s winds push water toward the shore, the rotation of the storm helps to pile up water along the coast, leading to storm surge flooding.

Overall, the rotation of a hurricane is a fundamental aspect of its structure and behavior. The counterclockwise circulation in the Northern Hemisphere (clockwise in the Southern Hemisphere) is a result of the Coriolis effect and influences everything from wind patterns to the development of the storm’s distinct features like the eye and eyewall.

6. Dissipation

The dissipation of a hurricane, also known as tropical cyclone dissipation, refers to the process by which a hurricane loses its strength and eventually ceases to exist as a tropical cyclone. There are several factors and processes that contribute to the dissipation of a hurricane:

1. Land Interaction: When a hurricane makes landfall, it begins to lose its primary energy source, which is warm ocean water. As the storm moves over land, friction from the land surface causes the storm to weaken. Land also disrupts the circulation pattern of the storm, leading to a decrease in wind speeds.
2. Cooler Water: Hurricanes thrive on warm ocean waters with temperatures typically above 80 degrees Fahrenheit (27 degrees Celsius). When a hurricane moves over cooler waters, it loses its heat and moisture source, causing it to weaken. This is why hurricanes often dissipate as they move northward into cooler ocean waters or encounter upwelling of colder water.
3. Vertical Wind Shear: Hurricanes require a low vertical wind shear, which means that winds at different altitudes do not change much in speed or direction. When a hurricane encounters strong vertical wind shear, it disrupts the vertical alignment of the storm, making it difficult for the storm to maintain its structure. This can lead to the dissipation of the hurricane.
4. Dry Air Intrusion: Hurricanes are fueled by the evaporation of warm ocean water, which provides moisture to the storm. When dry air from surrounding regions or upper-level troughs intrudes into the hurricane, it disrupts the convective process and can weaken the storm.
5. Eyewall Replacement Cycle: In some cases, a hurricane can undergo an eyewall replacement cycle. This occurs when a new eyewall forms around the existing eye. During this process, the old eyewall weakens and dissipates, while the new eyewall contracts and strengthens. This can cause a temporary weakening of the hurricane before it potentially strengthens again.
6. Interaction with Another Weather System: Hurricanes can interact with other weather systems, such as frontal boundaries or upper-level troughs. These interactions can disrupt the hurricane’s circulation and cause it to weaken and dissipate.
7. Loss of Warm Core: Tropical cyclones are characterized by their warm core, which is a region of warm, moist air at the center of the storm. When this warm core is disrupted, often due to one of the factors mentioned above, the storm can lose its tropical characteristics and transition into an extratropical cyclone.

Once a hurricane dissipates, it does not mean the end of its impacts. Even as a weaker storm or a remnant low, it can still produce heavy rainfall, gusty winds, and flooding in some areas.

7. Seasons

The hurricane seasons over the Atlantic Ocean take place between August and the end of October. In the eastern Pacific Ocean, on the other hand, it goes from May to the end of November. In total, the Atlantic Ocean usually sees about five or six hurricanes per year.

8. Consequences

Hurricanes, also known as cyclones or typhoons, are incredibly powerful and destructive natural phenomena. The consequences of hurricanes can be widespread and devastating, affecting various aspects of the environment, infrastructure, and communities. Here are some of the major consequences of hurricanes:

1. Heavy Rainfall: Hurricanes are associated with massive amounts of rainfall, leading to widespread flooding. This flooding can inundate homes, roads, and entire communities. The heavy rainfall can also cause landslides and mudslides in mountainous regions.
2. Storm Surge: One of the most dangerous aspects of hurricanes is the storm surge. This is a rise in sea level caused by the combination of strong winds and low atmospheric pressure. Storm surge can inundate coastal areas, causing rapid and extensive flooding. The surge can reach heights of several feet to over 20 feet (6 meters) in extreme cases, leading to significant damage to buildings and infrastructure.
3. Strong Winds: Hurricanes are characterized by powerful winds that can cause widespread destruction. These winds can damage buildings, tear off roofs, uproot trees, and create hazardous flying debris. High-rise buildings are particularly vulnerable to hurricane-force winds.
4. Tornadoes: Within the bands of a hurricane, tornadoes can form. These tornadoes can cause localized areas of intense damage, adding to the overall destructive power of the storm.
5. Infrastructure Damage: Hurricanes can cause significant damage to infrastructure, including roads, bridges, power lines, and communication networks. The destruction of these critical systems can hinder rescue and recovery efforts.
6. Power Outages: Strong winds and falling trees can knock down power lines, leading to widespread power outages. These outages can last for days or even weeks, impacting businesses, hospitals, and homes.
7. Displacement of People: Hurricanes often result in the evacuation of thousands of people from coastal and low-lying areas. Evacuees may be displaced for an extended period, leading to overcrowded shelters and the need for temporary housing.
8. Environmental Impact: Hurricanes can have a significant impact on the environment. They can damage coral reefs, destroy habitats for wildlife, and lead to contamination of water sources due to flooding and runoff.
9. Economic Losses: The total economic losses from hurricanes can be staggering. Rebuilding and repairing damaged infrastructure, homes, and businesses can cost billions of dollars. Industries such as agriculture, tourism, and fishing can also suffer long-term losses.
10. Health Risks: Hurricanes can create public health hazards. Floodwaters can be contaminated with sewage and chemicals, leading to the spread of diseases. Mold growth in flooded buildings can also pose health risks to residents.
11. Emotional and Psychological Impact: The trauma of experiencing a hurricane and its aftermath can have lasting emotional and psychological effects on individuals and communities. The loss of homes, possessions, and even loved ones can lead to feelings of grief, anxiety, and depression.

In summary, the consequences of hurricanes are wide-ranging and severe. They affect not only physical structures and infrastructure but also the well-being and livelihoods of communities impacted by these powerful storms.

9. Cyclonic waves

Cyclonic waves, also known as tropical cyclone waves or just “waves” in the context of hurricanes, are a fundamental characteristic of these powerful storms. These waves play a crucial role in the development and propagation of hurricanes. Here’s a closer look at cyclonic waves in the context of hurricanes:

Characteristics of Cyclonic Waves in Hurricanes:

1. Spiral Band Formation: Cyclonic waves are often associated with the spiral bands of clouds and thunderstorms that extend outward from the center of a hurricane. These bands spiral cyclonically (counterclockwise in the Northern Hemisphere and clockwise in the Southern Hemisphere) around the storm’s center.
2. Convection: These waves are regions of convective activity within the hurricane. Convective cells in these waves produce intense updrafts and downdrafts, contributing to the overall circulation of the storm.
3. Rainfall: Cyclonic waves are responsible for producing much of the rainfall associated with hurricanes. They can bring periods of heavy rain and intense thunderstorms as they move through an area.
4. Wind Patterns: The wind pattern within these waves is cyclonic, consistent with the overall rotation of the hurricane. Winds in these waves can be strong and gusty, especially near the outer edges of the storm.
5. Formation of Tornadoes: Tornadoes often form within these cyclonic waves, particularly in the outer bands of the storm. These tornadoes can be relatively small but still pose a significant threat due to their rapid formation and movement.
6. Impact on Intensity: Cyclonic waves can influence the overall intensity and structure of a hurricane. They can contribute to the organization of the storm’s circulation and the development of its core features, such as the eye and eyewall.
7. Propagation: These waves help propagate the energy and momentum of the hurricane outward from the center. They allow the storm to maintain its strength and continue to draw energy from warm ocean waters.

Importance of Cyclonic Waves:

1. Feeder Bands: These waves act as “feeder bands” for the hurricane, transporting warm, moist air from the ocean’s surface to the center of the storm. This process fuels the storm’s convective activity and helps sustain its strength.
2. Rainfall Distribution: Cyclonic waves play a role in distributing rainfall over a wide area. The bands of heavy rain associated with these waves can extend far from the center of the storm, leading to widespread precipitation.
3. Forecasting and Tracking: Meteorologists use observations of cyclonic waves to track the movement and intensity of hurricanes. Changes in the structure and organization of these waves can provide valuable information about the storm’s behavior.
4. Storm Surge: While not directly related to cyclonic waves, the overall rotation of the storm, influenced by these waves, contributes to the generation of storm surge. As the hurricane’s winds push water toward the coast, the cyclonic rotation helps pile up water along the shore, leading to storm surge flooding.

In summary, cyclonic waves are an integral part of the structure and behavior of hurricanes. They contribute to the storm’s intensity, rainfall distribution, and overall organization. Understanding these waves is crucial for forecasting and tracking hurricanes, as well as assessing their potential impacts on coastal areas.

10. Greatest hurricane in history

Determining the “greatest” hurricane in history can be subjective and depends on various factors such as wind speed, size, duration, and impact on human lives and infrastructure. Several hurricanes throughout history have left a lasting impact due to their extreme intensity and devastating consequences. Here are a few notable examples:

Hurricane Katrina (2005):

• Hurricane Katrina is one of the most infamous hurricanes in modern history. It made landfall on the Gulf Coast of the United States in August 2005 as a Category 3 storm.
• Katrina caused catastrophic damage, particularly in New Orleans, Louisiana, where the failure of the levee system led to widespread flooding.
• It resulted in over 1,800 deaths and caused an estimated $125 billion in damage, making it one of the costliest natural disasters in U.S. history.
• Katrina prompted significant changes in disaster response and planning, particularly in the realm of hurricane preparedness and levee construction.

Hurricane Maria (2017):

• Hurricane Maria struck the Caribbean in September 2017 as a powerful Category 5 hurricane, particularly devastating the island of Puerto Rico.
• Maria caused widespread destruction, including knocking out power to the entire island, destroying homes, and causing numerous fatalities.
• The official death toll from Maria in Puerto Rico stands at nearly 3,000, making it one of the deadliest hurricanes in U.S. history.
• The storm caused an estimated $91.6 billion in damages across the Caribbean, primarily in Puerto Rico.

Hurricane Harvey (2017):

• Hurricane Harvey made landfall in Texas in August 2017 as a Category 4 storm, bringing unprecedented rainfall and catastrophic flooding to the Houston area.
• Harvey stalled over the region, dumping over 60 inches (1,500 mm) of rain in some areas over a five-day period.
• The storm caused at least 68 fatalities in the United States and resulted in about $125 billion in damages, making it one of the costliest hurricanes on record.
• The flooding from Harvey displaced tens of thousands of people and had a significant economic impact on the region.

The Great Galveston Hurricane (1900):

• The Galveston Hurricane of 1900 is often considered one of the deadliest natural disasters in U.S. history.
• It struck Galveston, Texas, on September 8, 1900, as a Category 4 hurricane with estimated winds of 145 mph (233 km/h).
• The storm surge, estimated to be as high as 15 feet (4.5 meters), completely submerged the island city.
• The hurricane resulted in the deaths of between 6,000 to 12,000 people, making it the deadliest natural disaster in U.S. history.
• Following the storm, significant efforts were made to construct a seawall to protect the city from future hurricanes.

Typhoon Haiyan (2013):

• While not a hurricane in the Atlantic, Typhoon Haiyan (known as Yolanda in the Philippines) was one of the most powerful tropical cyclones ever recorded.
• It struck the Philippines in November 2013 as a Category 5 super typhoon, with winds reaching 195 mph (315 km/h) and gusts up to 235 mph (380 km/h).
• Haiyan caused catastrophic destruction, particularly in the city of Tacloban, where storm surges up to 20 feet (6 meters) inundated the area.
• The official death toll from Haiyan was over 6,300, with thousands more injured and millions displaced.
• Haiyan highlighted the vulnerability of coastal communities to extreme weather events and raised global awareness of the impact of climate change on tropical cyclones.

These hurricanes are just a few examples of the most significant and devastating storms in history. Each had far-reaching impacts on the affected regions, prompting improvements in disaster preparedness, response, and infrastructure to better mitigate the effects of future storms.