What Is a Hurricane?
A hurricane is a kind of tropical cyclone that includes organized thunder storms but no fronts. (Fronts are two air masses of different densities, such as cold fronts and warm fronts.) Tropical cyclones are measured in escalating degrees: When the winds in a cyclone are below 39 mph, it is considered a tropical depression. When the maximum sustained winds in a tropical cyclone reach 39 mph, it graduates to a tropical storm. Finally, when those winds sustain 74 mph or higher, the cyclone graduates further to a hurricane.
Hurricanes are not the same thing as tornadoes. Many people falsely believe that hurricanes are simply tornadoes forming over the ocean. In fact, the only thing the two have in common is that they are both swirling, destructive columns of air. The main differences between hurricanes and tornadoes are:
- Hurricanes can grow to be several hundred miles wide while tornadoes generally grow only a quarter mile wide.
- Hurricanes form over warm water in tropical oceans, developing far from the jet stream. Tornadoes form within storms over land — developing very close to the jet stream.
- Hurricanes can last as long as three weeks, while tornadoes last only about an hour.
- Hurricane winds usually clock in at less than 180 mph. Tornadoes can reach 300 mph.
- On average, about 10 hurricanes occur per year in the Atlantic Ocean, while the United States sees about 800 to 1,000 tornadoes per year.
- Typically, we’re warned several days in advance of an approaching hurricane, while we’re warned of a tornado no more than 15 to 30 minutes in advance.
Hurricanes form when low-pressure systems evaporate water from the ocean. As the vapor rises, it is normally carried away by winds. When no winds are present to carry the vapor away, it begins to spiral inwards on itself and forms a hurricane. As it spirals inward, it forms its own wind to draw up more vapor and send it inwards. (If they were near the jet stream, the winds would carry the vapor away and prevent the hurricane from forming.)
Hurricane Damage Scale
Hurricanes, like tornadoes, are defined by categories on the “Saffir-Simpson scale.” This scale measures the potential for damage caused by hurricanes, based on the strength of the sustained winds. (Sustained winds are those that last one minute or more.)
- Category 1 – Sustained winds of 74 to 95 mph. Minimal damage (shrubs, branches, unanchored mobile homes)
- Category 2 – Sustained winds of 96 to 110 mph. Moderate damage (trees, mobile homes, poorly constructed buildings)
- Category 3 – Sustained winds of 111 to 130 mph. Extensive damage (large trees down, small buildings damaged, mobile homes destroyed)
- Category 4 – Sustained winds of 131 to 155 mph. Extreme damage (exterior walls of buildings, roof failure on small buildings, doors and windows damaged extensively)
- Category 5 – Sustained winds greater than 155 mph (like during Hurricane Katrina. Catastrophic damage (roof failure on many buildings, some buildings may be completely destroyed)
The Saffir-Simpson scale measures the potential damage from the hurricane itself. It does not measure potential damage from the storm surges, rain and other hazards that may accompany hurricanes. This is because such things are difficult to account for, although scientists and meteorologists are working to create a more detailed hurricane rating system.
Interesting Hurricane Facts
- Hurricanes can unload 2.4 trillion gallons of rainwater each day.
- In the Atlantic, hurricane season starts on June 1. In the Pacific, it starts on May 15. Both seasons end on November 30.
- 40 percent of the hurricanes in the United States hit Florida.
- Hurricanes can grow to be 400 to 500 miles across with an eye of 20 miles across.
- Many hurricanes cause severe flooding. This flooding is responsible for 90 percent of the deaths caused by hurricanes.
- Thunderstorms within hurricanes can turn into tornadoes.
- Hurricane, cyclone and typhoon all mean the same thing. The name simply tells where it formed. Hurricanes form over the North Atlantic or Caribbean, typhoons form over the western part of the Pacific Ocean, and cyclones form over the Indian Ocean.
- Hurricanes were first named by an Australian weatherman in the 19th century. Clement “Wet” Wragge would name violent storms after people he disliked.
- Hurricane Ginger, North Carolina in 1971, lasted for three weeks.
- Hurricanes didn’t start getting male names until 1979.
- Particularly devastating hurricanes have their names “retired” from the list of names. For example, there will never be another hurricane named “Katrina.”
- The flexible trunk of the palm tree is thought to be an evolutionary step for the plants to bend in hurricane winds without breaking.
What to Do Before, During and After a Hurricane
The best way to survive a hurricane is to be prepared. Many organizations, such as FEMA, offer tips and information on how to prepare yourself and your family for the event of a hurricane. It’s best to educate yourself is long before the hint of a hurricane. There will be no time to sort it out after you’ve gotten the warning.
- Identify the elevation of your property and learn whether or not it is flood-prone. This will tell you how your property might be affected during a storm surge or flooding.
- Learn where levees and dams are in your area, and understand how they might affect your property during a hurricane.
- Assemble emergency kits for each member of your family, taking into account special needs for infants, the elderly or the infirm or handicapped. Also consider your pets’ needs.
- Learn the evacuation routes out of town and know how to get to higher ground.
- Establish an after-storm meeting place in case your family is not all together when it hits. Agree on a few of alternate meeting places in case one or more is inaccessible or unsafe.
- Make your home resistant to storms by installing storm windows and doors, reinforcing your garage door, and adding straps or clips to help keep your roof attached to your house.
- Keep trees and shrubs trimmed to reduce wind resistance.
- If a hurricane is imminent, bring in all outdoor furniture, garbage cans and yard decorations. These can fly loose and cause serious injury or damage to yourself, your home and others.
- Make sure your rain gutters and downspouts are clean and in good repair.
- If you own a boat, make plans to secure it.
- Install a generator.
- Consider building a safe room or storm shelter — an interior room without windows — where your family can hunker down.
- If you live in a high-rise, know where to take shelter on the lower floors. Winds increase in intensity at higher elevations, so get to the lowest floor you can, but be mindful of the possibility of flooding and try to stay above that level. Generally, this will be below the 10th floor but above the 2nd.
When a hurricane is imminent, you may wonder whether you should evacuate. You should evacuate if:
- You live in a mobile home
- You live near a body of water or on a floodplain
- The authorities advise you to evacuate
If you are not evacuating, be sure to do the following:
- Secure storm windows and doors.
- Close blinds and curtains and otherwise block windows to hamper flying glass in case of breakage from winds or flying debris.
- Listen to the radio or TV for instructions and advisories.
- Turn off propane tanks.
- Turn off utilities if you are instructed to do so. If utilities are to be left on, set your refrigerator thermostat to its lowest setting. This will help preserve food longer if the power goes out.
- Fill bathtubs and sinks with water to ensure a clean supply for drinking or for hygiene.
- Avoid using the phone except for genuine emergencies. Emergency personnel will need the lines free so they can communicate with each other to save people.
- Stay indoors, avoiding windows and glass doors.
- Secure and brace exterior doors and close all interior doors.
- Get into a small interior room using anything you can as a shield, such as tables, mattresses and anything else that might deflect or absorb the impact of flying debris.
- Do not use elevators.
It’s not necessarily over when the winds stop blowing. You’ll still need to take steps to ensure your safety after a hurricane.
- Continue listening to the radio for updates and other advisories.
- Stay alert for reports on flooding and extended rainfall.
- If you are separated from your family, go to an agreed on meeting place or to a Red Cross shelter.
- If you have evacuated, return home only when the authorities say it is safe. If you have long-term housing needs, contact FEMA.
- Drive only if necessary and avoid flooded roads even if they look slow-moving or shallow. There can be strong currents and heavy debris just below the surface.
- Avoid loose or dangling power lines. Report them if possible.
- Before entering your house, walk around and inspect it for gas leaks, loose power lines and structural damage. It may not be safe to enter.
- If you smell gas, or if there are flood waters, do not go into your house.
- Use battery powered flashlights, turning them on before entering the building. (Activating a flashlight may throw a tiny spark from the batteries that could ignite any leaking gas.)
- Keep your pets under control and be aware of any wild animals that may roam into an area. If you have to reach into a debris pile, poke around with a stick to discover snakes or other animals that may be sheltering there.
- Avoid tap water until you’re sure it’s not contaminated.
- Wear protective clothing. Any water you may come in contact with could be contaminated, and open wounds will become infected.
- Never use a generator in an enclosed space. Carbon monoxide can build up faster than it can be ventilated, and it can linger long after the generator has been shut off.
Hurricane Survival Kit
There isn’t a single place in the United States that doesn’t periodically experience some kind of natural disaster. Therefore, a basic emergency kit is a must for every home. A basic kit includes:
- One gallon of water per person per day that you expect to remain in “survival mode.” Typically, this is about three days. Remember to include your pets. Small pets like cats or birds may use less, but a large dog may require as much as a human being. Check with your vet to learn how much water your pet will need.
- A three-day supply of non-perishable food.
- A battery-powered or hand-cranked radio, NOAA radio and flashlight with spare batteries.
- A first-Aid kit. Check your supplies regularly. Some elements of this kit may have expiration dates.
- Prescription medications.
- A shrill whistle to signal for help. Every member of your family should have one.
- Garbage bags and moist towelettes for personal hygiene.
- Dust masks to filter contaminated air.
- Plastic sheeting in case you have to shelter in place.
- A basic tool kit with wrenches, pliers and various kinds and sizes of screwdrivers (to turn off utilities or to affect repairs).
- A manual can opener.
- Maps of the local area.
- Cell phones with solar chargers.
- Rain gear and heavy clothing for protection from the elements. (If you expect flooding, have waders as well. Flood waters can be seriously contaminated even if they look clear, and some teem with viruses too.)
- Things to entertain small children (comic books, puzzles and games).
- A wooden or other non-conductive pole to push potentially electrified wires out of the way.
Also useful to keep near your survival kit is a water-tight case, such as a small, portable safe, to keep valuables and important documents (birth certificates, insurance documents, pink slips, financial documents, etc.). When you grab your survival kit, grab this container as well.
Infants will have their own certain needs. If you have an infant, be sure to include the following in your emergency kit:
- Formula (check every six months for expiration)
- Rash ointment
- Powdered milk (check periodically for expiration)
- A few baby blankets
- Infant cough or cold medications
Older adults may require a few specialty items in their kits as well:
- Spare dentures
- Denture needs (adhesives, cleaners, etc.)
- Extra eyeglasses
- Prescription medication
- Batteries for medical equipment
- Oxygen masks and accompanying tanks
If you have a handicapped family member, take note of their special needs and include any medications or disposable supplies (catheters, adult diapers, wipes) as well as any equipment they may need in easy reach. Be prepared to help them quickly get to safety.
Some goods in your emergency kit will have expiration dates. Use them normally when there is no storm. This way, you can circulate them out before they expire. Always remember to restock them as if they were in your cabinet.
Educate Your Children
It is of utmost importance that your children know and understand the seriousness of a hurricane. Left to their own devices, very young children may not grasp just how bad a hurricane can be, and older children may downplay it — especially if they have never experienced a truly scary one before.
Conduct regular drills. Once a month is a good frequency for those who know what to do. With small children, treat it as a game with a reward for doing things properly. With older children, you might allow them to invite their friends over to join in. Whichever the case, be sure to openly talk about how knowing what to do during a hurricane can save their lives. It might be tempting as a parent to shelter your children from the darker aspects of such a disaster, but it will help them better understand the importance of preparedness if they know the gravity of the situation.
If someone in your family is having trouble with any part of the plan, look at the situation and address it gently with the individual. Perhaps a child’s emergency kit is too heavy, or your teenager’s kit winds up stuffed in the back of their closet and is difficult to get to. Work with them on a solution to ensure their safety. Your child may have too many toys stuffed into their kit, or their extra clothing may just be too heavy. Your teenagers may need to find another place to store their kits within easy reach. The important thing is that they understand the importance of getting to safety quickly and with their emergency kits.
What is the difference between a hurricane watch and a warning?
A hurricane watch advises us that the conditions are right for a hurricane to form. Weather experts monitor conditions and let people know, usually over an NOAA radio, that there is a possibility that a hurricane may form.
A hurricane warning advises us that a hurricane has formed. If a hurricane watch is meant to alert you to a potential danger, a hurricane warning is a call to action. Typically, you’ll have a few days to board up windows/doors and sandbag in places where boards may not be practical.
Why do we name tropical storms? Who names them?
Storms used to be identified by the year and order in which they occurred. But, this led to confusion when two or more storms cropped up simultaneously. In the West Indies, hurricanes were named for saints if they happened to fall on a saint’s feast day. Possibly inspired by Clement Wragge, an Australian weatherman who often named violent storms after people he didn’t like, many weather organizations found it easier and less confusing to apply names, specifically women’s names, to hurricanes. Women’s names were used exclusively until 1978 when it was decided to include male names starting in the 1979 season.
Names for hurricanes are selected from a list drawn up by the World Meteorological Organization. Lists are created for each hurricane season and alternate between male and female names. This list undergoes a six-year rotation. If a storm is particularly deadly, its name may be retired from the list and never used again. Katrina is an example of one such instance.
What causes a hurricane?
Hurricanes are formed when warm air evaporates ocean water and draws it up. The vapor is normally taken away by winds where it cools and falls back to the ocean as rain. When no winds are present, the vapor falls back down and mixes with the rising warmer vapors. As it falls, it begins to spiral in on itself. This cycle of rising and falling vapor feeds the storm until it encounters dry air, finds a good wind or becomes a hurricane.
What is a hurricane made of?
Hurricanes are made up of air and water at their most basic elements. It’s the interaction of these things that creates the spiral that becomes a hurricane. As the water rises, its latent heat is drawn off as it cools. This heat causes more water to be drawn up and evaporate. This leaves behind a low-pressure area. Nearby, high pressure rushes in to fill the void, bringing with it more warm, moist air — and the cycle begins again. As long as warm, moist air can be found, the hurricane will feed itself, growing larger and more powerful until it finds dry air. With no moisture on which to feed, the hurricane will weaken.
What was the deadliest hurricane on record?
The deadliest hurricane ever recorded was the Great Hurricane of 1780, which resulted in a reported 22,000 to 27,501 deaths. Though no record remains of its track and strength, its appearance in the Lesser Antilles during the American Revolution caused heavy losses to natives and to the British and French fleets undergoing operations in the area. It occurred between October 10th and 20th, 1780.
Hurricane Mitch struck Central America with a loss of almost 20,000 souls due mostly to catastrophic flooding. Occurring in October of 1998, it also left about 2.7 million people homeless. This hurricane happened between October 22nd and November 9th.
The Galveston Hurricane of 1900 was the deadliest to hit the United States. Between 6,000 and 12,000 people were reported dead, with most official reports listing 8,000. Unfortunately, there were no records to prove the existence of many who died in that hurricane, save the memories of friends and family. While the number is officially listed at 8,000, historians and genealogists put the number closer to 12,000. Limited communication and a number of wrong guesses and assumptions at the U.S. Weather Bureau left Galveston woefully unprepared for the storm that lasted September 6th-8th.
What was the costliest hurricane?
Hurricane Katrina was the costliest hurricane ever recorded. Property damage equalled $108 billion. Federal funding to repair infrastructure, construct temporary housing, fix schools and provide general relief has added up to more than $127 billion. Insurance losses, including flood damage, are estimated at $60 billion.
Hurricane Katrina Facts
- Hurricane Katrina started out as a tropical depression located near the southeastern Bahamas.
- The maximum sustained winds at the hurricane’s peak were 175 mph.
- As Katrina passed over the Gulf of Mexico, it strengthened into a category 5 hurricane, but it then picked up some dry air and weakened to a category 3.
- At landfall (when it touched land after being over sea) at the Broward/Miami-Dade county line in Florida, Katrina’s pressure and sustained winds were 984 millibars and 80 mph. (A millibar is a unit of barometric pressure.) It was a category 1 at this point.
- At landfall at Buras, Louisiana, Katrina’s pressure and sustained winds were 920 millibars and 125 mph. It was a category 3 at this point.
- At landfall at the Louisiana-Mississippi border, Katrina’s pressure and sustained winds were 928 millibars and 120 mph. If wind damage alone were considered, Katrina was category 1 or 2 at this point.
- The lowest pressure recorded in Katrina was 902 millibars.
- The storm surge height was 27.8 feet at Christian Pass, Mississippi.
- Just south of Dauphin Island, a buoy measured peak waves at 55 feet.
- The storm surge went inland for six miles, but up rivers and streams it reached 12 miles.
- About 80 percent of New Orleans was under water during the flooding.
- Most of the damage in New Orleans was caused by the levee failures.
- Katrina wreaked $108 billion in damages, making it the costliest in U.S. history. This doesn’t include insurance losses and post-storm federal money for rebuilding, which cost another $187 billion.
- 1,200 lives were lost during the storm, during the floods, and in the tragic aftermath.
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