HURRICANE RESEARCH QUESTIONS:

1.     What is a hurricane?

 

A hurricane is a low pressure area that has high winds.  When water vapor condenses it releases heat that was collected to evaporate.  Then the hurricane grows. It lives over warm oceans.  The hurricane has a very big and thick layer of clouds with an eye. The eye is the center of the hurricane around which the air rises and cools down. The cool air condenses again and forms more heat. Then it warms the air, which rises more. Cooler air swoops down to replace it, causing wind. The earth’s rotation makes winds spiral and spin.

 

2.     What causes hurricanes to form?  Why are they called "heat sinks" in the atmosphere?

 

A hurricane is caused when very low pressure develops with a rapid inflow of air.  This forms a storm.  As the walls of the eye spin in a vertical, counter clockwise direction, it takes up moist warm air that has come from the ocean.  As it gets higher into the atmosphere, it cools and the water comes down as condensation.  The heat then is distributed throughout the other parts of the hurricane making it stronger.  The air in the atmosphere sinks through the eye and is warmed by compression.  The heat in the ocean is put in to the air and the process occurs again.

 

  It is called a heat sink because it drains heat from the ocean and lower atmosphere, into the upper atmosphere, and space.

 

3.     Where do most hurricanes develop on Earth?  Why do they develop here?

 

Hurricanes form between 5 degrees and 30 degrees latitude and move toward higher latitudes. The air over tropical oceans is very warm and humid. In low pressure, the storm develops and the winds increase. The rotation of the earth causes it to spin rapidly. Thus this forms a hurricane.

 

4.     Is there a "hurricane season"?    What time of year do most hurricanes develop?

 

In the Northern Hemisphere hurricane season takes place from June 1^st through November 30^th.  The peak time is the first week of September. In the Southern Hemisphere it’s the exact opposite. I think that it’s because the water is warmer during that season.  For a hurricane to form you need a warm layer of water at the top of the sea with temps greater than 80ºF (26.5ºC).

 

The primary time of year for getting tropical cyclones is during the summer and autumn: July-October for the Northern Hemisphere and December-March for the Southern Hemisphere (though there are differences from basin to basin). The peak in summer/autumn is due to having all of the necessary ingredients become most favorable during this time of year: warm ocean waters (at least 26°C or 80°F), a tropical atmosphere that can quite easily kick off convection (i.e. thunderstorms), low vertical shear in the troposphere, and a substantial amount of large-scale spin available.

 

While one would intuitively expect tropical cyclones to peak right at the time of maximum solar radiation (late June for the tropical Northern Hemisphere and late December for the tropical Southern Hemisphere), it takes several more weeks for the oceans to reach their warmest temperatures. The atmospheric circulation in the tropics also reaches its most pronounced (and favorable for tropical cyclones) at the same time. This time lag of the tropical ocean and atmospheric circulation is analogous to the daily cycle of surface air temperatures - they are warmest in mid-afternoon, yet the sun's incident radiation peaks at noon.

 

5.     How many tropical disturbances generally occur in one season?  How many become named storms?  How many affect the United States?

 

About 73 tropical disturbances general occur in one season. Almost all of them become named storms. Not to many of these storms hit the United States of America because most of the storms form in the Atlantic Ocean.

 

6.     Where do the hurricanes that threaten the U.S. generally develop?

 

The only two places that hurricanes have formed, which would a threat to the U. S. is the East Pacific Ocean, and the Western Atlantic Ocean.  There have been 15 hurricanes that have formed already from the Eastern Pacific Ocean. And, there have been 12 hurricanes from the Western Atlantic Ocean. But, hurricanes that strike the U.S. usually develop North of the equator between 5 and 30 degrees. So obviously, if there is a place where hurricanes can start that threaten the U.S. you need a large warm body of water to be able to have a hurricane occur.

7.     Describe the life cycle of a tropical cyclone.  Describe each of the three stages of these storms and what conditions determine when another stage is reached.  Include the weather map symbol for each type of storm.

 

Tropical cyclones have three stages in order they are tropical storm and hurricane. The lowest has a wind speed at about 30 mph, the next has a wind speed of about 40 mph and the third the all infamous hurricane can have from 74 mph to well over 155 mph. Also the way to measure a hurricane is by the “ Saffiar-Simpson” scale which ranges it from 1-5 in force. These are the symbols for,

Tropical depression = L

Tropical storm =

Hurricane =

 

8.     What conditions are necessary to sustain the strength of a hurricane?  When and why does a hurricane die out?

 

One of the most important conditions to sustain the strength of a hurricane is the temperature, which is 78 degrees F.   You have to have extremely warm water to sustain the strength of a hurricane.   When a hurricane passes over warm water it strengthens and when it passes over cold water or land it usually disperses.  A hurricane may pass over land and somehow keep its strength, and pass over into warmer water, making the hurricane stronger.  In order for the wind speeds to pick up in a hurricane the barometric pressure must be low, if the barometric pressure is higher, then the wind speeds will drop.   The hurricane season begins on June 1st and ends on November 30th.  The peak of the hurricane season is the first week in September, or September 10th to be exact.

 

9.     What is the direction of circulation in a hurricane in the Northern Hemisphere?  How does this compare to rotation in the Southern Hemisphere?

 

The direction of circulation in a hurricane in the Northern Hemisphere is counter clockwise and the direction in the Southern Hemisphere is clockwise because of the Coriolis effect which causes everything on the northern hemisphere to move to it’s right and everything in the southern hemisphere to move to it’s left. 

 

10. What is the "eye" of a hurricane?  Describe any other "parts" of a hurricane?

 

·         The eye of a hurricane is the center of the hurricane that the hurricane revolves around, but there is a very calm center to the hurricane.  Scientist call the center of the hurricane the “eye” of the storm.  Inside the eye it is very, very calm. 

 

·         The other parts are: the eye wall, whish is the air and rain that makes up most of the rest of the hurricane surrounding the eye.  The eye wall is probably the most violent of the parts of the hurricane.

 

·         The third part of the hurricane are the cloud bands.  The cloud bands contain a large number of thunderstorms and will drop much rain as each passes over an area.

 

11. What is the usual amount of rainfall during a typical hurricane?  List any factors that affect the amount of rainfall in a particular storm.

 

It depends how much rainfall there is, it would be anywhere from 4-18 ft.  In a hurricane what helps to flood, is the rain, waves, water, and storm surge (flooded).

 

§        Two factors that affect the amount of rainfall are the speed that the storm is traveling and its distance from the sea.  A slowly moving storm will stay over an area for a longer amount of time and will drop more rainfall.  A storm that is closer to the sea will be closer to its source of water.

 

12. What is normal barometric pressure  in millibars (mB)  and how does it compare to the pressure in a hurricane?  How does it change as the hurricane approaches?  What is the lowest barometric pressure recorded in a hurricane in the Northern Hemisphere?

 

The average barometric pressure is 1020mb (milibars).  The Hurricane Andrew had a much lower pressure of 922mb.  Leslie had a barometric pressure of 1005 at 1:00 AM October 5.  So that means hurricanes are very low-pressure storms. Right before a hurricane hits an area, a barometer will drop and rise repeatedly but will be lower in the end. The lower the barometric pressure, the higher the winds in the storm.

 

13. Where are the strongest winds in a hurricane located?  Why are they so strong there?

 

The strongest winds in a hurricane are located in the eye wall. This is the strongest wind because it is located near the center of the cyclone. The strongest winds are on the right side of the storm, adding forward speed to the rotational speed.  But on the left the forward speed is the opposite of the rotation speed, so the total speed is less.

 

14. What is the Saffir-Simpson Scale of hurricane classification?  What are the differences between each category of hurricane?

 

The Saffir-Simpson Scale is a scale that tells the categories of hurricanes.  There are five categories that explain the level of each hurricane.  Category one has minimal damage.  The damage is to shrubbery, trees, and non-permanent mobile homes.  The central pressure is greater than 980mbor 28.94inches.  The wind speed is 74 to 95mph or 64to 83kts.  The surge is 4 to 5feet.  Category two has moderate damage.  The damage is to shrubbery, leaves, and branches.  Some trees are blown down, not well made signs have extensive damage.  There is also damage to windows and roofing materials and minimal damage to buildings.  The central pressure is 965 to 979mb or 28.50 to 28.91inches.  The wind speed is 96 to 110mph or 65 to 96kts.  The surge is t6 to 8 feet.  The third category has extensive damage.  Leaves and branches are ripped from the trees, big trees are blown down, and poorly made signs are blown down as well.  There is some damage to roofing, windows, and doors.  Little damage is done to small buildings; mobile homes are destroyed.  Major flooding along the coast.  Near the coast small structures are destroyed and large structures are damaged by waves. Central pressure is 945 to 964mb.  The wind speed is 111 to 130mph or 97 to 113kts.  The surge is 9 to 12 feet.  The fourth category is extreme damage.  The following are blown down: shrubs, trees, and all signs.  Extensive damage is to roofs, windows, and doors.  The mobile homes are demolished.  Flat terrain inland about 6 miles and 10 feet high or less, is flooded.  Battering waves cause major damage to lower floors of buildings near the shore.  There is extensive erosion of beaches.  The central pressure is 920 to 944mb or 27.17 to 27.88.  The wind speed is 131 to 155mph or 114 to 135kts.  Surge is 13 to 18 feet.  Category five is catastrophic damage.  There is considerable damage to roofs of buildings.  Major damage to windows and doors.  Glass shatters in windows and doors. Buildings become feet high, which are within 1500feet of  shore.  Low laying escape route become unusable due to rising water. Many of residential areas on low grounds are evacuated.  Central pressure is less than 920mb or 27.17 inches.  Wind speed is more than 155mph or 13kts.  The surge is greater than 18 feet.

                                                                                                                                                                                                                                     

 

15. How are similar storms known in different parts of the world?

 

Tropical depressions, tropical storms, hurricanes, cyclones, baguios, willy-willies, and typhoons are all named for specific reasons. For example, tropical cyclones, located near North America, are known as hurricanes. One that is not mentioned up above, is the tornado. A tornado is an atrocious whirlwind that usually treads over flat lands and can sometimes be associated with a hurricane. In Eastern Asia, violent ocean storms are not called hurricanes, but typhoons. These storms are much more severe than that of a cyclone and a hurricane put together. Japan, China, Korea, and much of Eastern Asia get hit with harsh winds, severe rain conditions, and flooding. Cyclones are one step ahead of hurricanes. Bringing down harsh rain and weather, this traveling ocean whirlwind can usually be found in or around the southern coast of India. Tropical depressions are basically just tiny storms that happen in different parts of the world, but if in warm waters, it could develop into a tropical storm. Tropical storms bring in thunderstorms and rain. Baguios are the name for a hurricane in China. Willy-willies are hurricanes, but they are usually located near Australia. Many of these hurricanes are located in much warmer waters than in those of the Gulf of Mexico, the Pacific Ocean, and the Atlantic Ocean. The special thing about hurricanes though, is that each one of them is named and they go in alphabetical order. Many of these storms are different and in different languages, but in the end, they mean the same thing.

 

16. How are hurricanes named?  Is there a pattern?  What is it?  Does it change from year to year?  When did we start naming hurricanes?

 

Hurricanes are named in alphabetical order, which starts at the beginning of the alphabet every year. We name hurricanes so we don’t get confused. If there are so many hurricanes in a year that the names pass through the entire alphabet, then the hurricane’s names start back at the beginning.  Male and female names are switched for each storm. The World Meteorological Association uses and rotates six lists of different hurricane names. Hurricanes have been given female names since 1953.  In 1979 hurricanes were given male and female names.  Hurricanes in the Atlantic Ocean can have French, English, or Spanish names. A tropical cyclone is named when the wind speed is 39 mph or more, and it becomes a tropical storm. Hurricane’s names are retired only if they are extremely destructive or deadly. When a name is retired a new name is chosen.  Some retired hurricane names are Allen, Bob, Cleo, Donna, Elena, Fran, George, Hortense, Joan, Mitch, and Opal.

 

17. List the names of hurricanes that have been retired.  When is hurricane's name retired?

 

Retiring a hurricane means that the name is never to be used again. When a really good athlete retires, his or her jersey or number is usually retired. Same with the biggest and most destructive storm in the tropics which is the hurricane. It makes a similar retirement. Hurricane names can get retired, often for ten years or more. They also retire major hurricane names because there may be confusion in further generations if it was a major storm and many people were killed.

     When a storm name is retired from the Atlantic's list of names, member countries of the World Meteorological Organization from that region choose a new name. The country most affected can request that the storm's name be removed off of the list.

 

Names of Retired Hurricanes:

 

 

18. Describe some of the major hurricanes in history.  When did they occur?  List data from the storm, wind speed, rainfall, path, etc.

 

Some of Eastern North America’s Most Devastating Hurricanes
By Caitlin Fellows

North America has had many hurricanes, most of which we'll never know about, but what were some of the worst?

In the past century, devastating hurricanes in the east Atlantic were started off by the one lasting from August 27th to September 18th in 1900.  It is known as the Galveston Hurricane causing the most damage in Galveston, Texas.  Wind speeds reached 77 miles per hour and at one of its fastest traveled east at 120 miles/hour.  It caused around 8000 deaths and $5,000,000-50,000,000 in damage.

Fifteen years later, 90% of the buildings in a large area of Louisiana south of New Orleans were lost form a hurricane.  Two hundred, seventy-five people died from not heeding safety warnings.  The wind speeds reached 106 miles/hour and it caused $5,000,000-50,000,000 damage also.  Not as much as Audrey, however, in June 1957 who caused $50,000,000-500,000,000 loss and over 600 casualties.  Audrey had winds that reached 85 miles/hour and had a travel speed of 100 mi/hr.  Around 160 of the people who died were under the age of nine, and almost all the homes in the areas of Texas and Alabama it most affected were destroyed.

Although it was very devastating, Audrey wasn’t quite as bad as the one that followed 12 years later, force five hurricane, Camille.  Causing devastation in Mississippi, Louisiana, Alabama, the Virginias, Florida and a few other US

states, Camille had winds exceeding 150 miles/hour traveling at a speed of 100 mi/hr.  With it 600 deaths were brought along with $500,000,000-5,000,000,000 worth of damage.  It was the first hurricane on record to move inland from the east to northeast part of Florida.

Although it only caused $50,000,000-500,000,000 of damage, considerably less than Camille did, Gilbert has been debatably said to be an extremely devastating hurricane.  It occurred in September of 1988 and was the cause of over 300 US deaths.  It caused damage in the Caribbean, Jamaica, the Yucatan Peninsula, Mexico, northern Texas and Oklahoma.  It traveled inland with winds of 184 mph and a barometric pressure (the pressure of the atmosphere pushing on the Earth) of 888 millibars.  It was the strongest hurricane on record as of September 1988 with 40-foot waves on top of a giant storm surge (a wall of water that is pushed ahead of the hurricane). 

One year later was the year of Hugo.  Hugo caused about 7 billion dollars in damage and had a 20-foot storm surge.  Although it only caused 80-100 deaths it was the strongest storm yet to hit Florida since Hurricane Hazel in 1954.  Hugo completely devastated the barrier islands of South Carolina so that protection against ocean storms is much less now.

In August of 1992 over 2 million people were evacuated from their homes due to Hurricane Andrew who hit the Gulf of Mexico, Florida, and the southern and central parts of Louisiana.  It caused about $26.5 billion in damage and is considered to be the most devastating hurricane to hit the US in the 20th century.  It brought winds of over 170 miles per hour and caused over 60 deaths.

The most recent hurricane to be considered very devastating was Hurricane Floyd in 1999 that left his mark in North Carolina and Virginia.  It also left 1.325 billion dollars in damage plus $6 billion for flood damage.  Floyd was 600 miles wide and dumped a record amount of rain.  With the rain came floods and a great loss of livestock, crops and 7000 homes that were completely destroyed along with 1700 that were uninhabitable.

These hurricanes were all in the past century and they are only a few that occurred.  I wonder what hurricanes we'll face this century.

 

 

 

19. What is the difference between a hurricane watch and a hurricane warning? What actions should be taken during each?

 

A hurricane watch is different than a hurricane warning.  A hurricane watch means that there are hurricane force winds possible in the next 36 hours.  A hurricane warning is more important and dangerous.  A hurricane warning means that hurricane force winds are likely in the next 24 hours.  Precautions that should be taken for hurricane watches are: check food, batteries, emergency tools and supplies.  Also monitor the latest advisories.  Safety precaution for a hurricane warning are to leave low lying areas leave mobile homes, board windows and protect with storm shutters.  Both of these watches and warnings should be taken very seriously.

 

20.  Describe the four main causes of destruction in a hurricane.

 

In hurricanes there are four main causes of destruction.  The least destructive of the causes is the rain.  It is the least destructive because of the small amount of the damage it causes; some of the damage that causes can be listed as erosion, leaks in roofs, and other water damage.  The second least destructive is the storm surge flooding.  The hurricanes create a dome of water that causes floods when it reaches land.  Then the floods would continue over the land, demolishing houses and drowning people.  The second most destructive force is the large waves.  They can reach hights of thirty feet.  Once it reaches the land it acts like a storm surge flood except more forceful when it crashes into the land. The most destructive of the causes is the wind damage.  The winds are the main cause of all of the destruction forces.  As the hurricane spins it creates fast winds.  When the winds of a hurricane get fast enough they can knock over trees, houses, cars, and just about anything else that you could think of.  However, if people are careful and they leave in time they will be fine.

By Adam Patch and Mathieu Nichols

 

21.Do two hurricanes ever interact with each other?  What is the Fujiwhara effect?

 

Hurricanes can interact with each other and it can happen time after time.  In the earth’s history there have been many occurrences where two hurricanes interact with each other.  The most recent was the event in 1995 with the tropical storm Iris and hurricane Humberto.  When something like this happens, it is called the Fujiwhara effect.

In the case of a Fujiwhara, the two storms would circle each other.  This is thought to happen when they are around 900 miles apart.  Although hurricanes (and tropical storms) occur all the time, it is very rare for two of them to interact and cause the Fujiwhara effect.