The following questions were answered by meteorologists Barbara McNaught Watson and Al Peterlin.
Q: How does a hurricane start?
A: A hurricane starts with a few basics, one of which is a very warm ocean to serve as a source of energy. The second is some kind of disturbance in the atmosphere, which we call instability such as a front, a depression, or a wind shear (change) area. With some energy, lots of moisture, proper upper level winds, and a trigger, up blows a tropical storm that can grow into a hurricane. (Al Peterlin)
Q: How do you know when a hurricane is coming?
A: Meteorologists track hurricanes using satellites. We take measurements around the storm that tell us what the winds are. A hurricane moves with the winds in the mid level of the atmosphere similar to the way a pine cone would float down a stream. Since you can see where the stream is going, you can somewhat predict where the pine cone will go — downstream. This is how we watch hurricanes.
When it looks like the hurricane is a day or two away from land, we start to alert people that they need to prepare in case the storm hits. We use special computers to help us predict how the stream of air will move and how the hurricane will move in that stream of air.
We still have much to learn. At 24 hours, our accuracy averages to within about a 125 miles of where a hurricane hits land. So the hurricane warning goes out for a rather large portion of the coast in case the storm suddenly veers to the right or left.
As your pine cone continues downstream, it may move into a pool of water that seems to have no specific direction to it and the pine cone may meander around. This can happen with hurricanes, too, and makes them very unpredictable. Some hurricanes have sat over the same area for a couple days or have done loops and meandered around for almost a month before making landfall on a coast. (Barbara McNaught Watson)
Q: When was the first hurricane ever recorded by meteorologists? Where was it?
A: The earliest records of hurricane encounters come from Christopher Columbus. He experienced the fringes of a hurricane in 1494, when he neared Hispaniola. Records in the early settlements in Virginia in the 1600s and 1700s talk of great hurricanes that caused the level of the Chesapeake Bay to rise 12 to 16 feet in what is known as the storm surge.
But these records did not come from meteorologists. Benjamin Franklin was one of the country's first meteorologists. Thomas Jefferson and George Washington also kept good weather records. The United States has kept track of hurricane paths since 1871. The Army Signal Corps monitored the weather until the birth of the U.S. Weather Bureau, which later became the National Weather Service in 1970. Back in the 1800s, much of our information came from ships that traveled to and from the Caribbean.
The first recorded hurricane in 1871 formed near the Florida Keys and moved west into Texas. Of the six storms that year, four of them affected Florida and Georgia. (Barbara McNaught Watson)
Q: What is the difference between a hurricane and a tornado?
A: Hurricanes start over warm ocean water. The water acts as a source of energy waiting to be activated by a storm front or an upper level disturbance (a front above the surface). Hurricanes start over the oceans and die once they move over land, although they can do a lot of damage even as they weaken. Hurricanes are very, very large.
Tornadoes are much smaller events, usually lasting only a short time and covering only a small area, but they are very, very violent winds. Tornadoes need the collision of very warm moist air and very dry cold air and some upper level winds to act like a chimney to move energy away from the storm. (Al Peterlin)
A tornado starts as a thunderstorm and then turns into a funnel cloud. A hurricane starts as a bunch of clouds that spin around and turn into a tropical storm. They both can start over water, and both of them have eyes. (Barbara McNaught Watson)
Q: Which is more dangerous, a hurricane or a tornado? Why?
A: Deciding whether a tornado or a hurricane is more dangerous is difficult. They are both very powerful, but hurricanes are much much bigger and so they do far more damage. I guess I would say, then, that a hurricane is worse than a tornado. (Barbara McNaught Watson)
Q: How long does it take for a bad storm to turn into a tornado or hurricane?
A: A hurricane usually takes days to develop. The fastest a hurricane might form is in 48 hours or two days. If a cluster of thunderstorms already exists then it might only take a day.
A tornado, however, is spawned from a thunderstorm. A thunderstorm takes about 30 minutes to form and reach maturity (when thunder and rain occurs). Some tornadoes, which are called "landspouts" over land and "waterspouts" over water, can develop during this stage. The stronger tornadoes are believed to come from thunderstorms that are rotating (or spinning) slowly. In these storms, it is believed to take about 45 minutes for all the ingredients to come together. That is not very long! (Barbara McNaught Watson)
Q: Have you ever been inside the "eye" of a hurricane or tornado? If so, what was it like?
A: I have never been in the eye of a hurricane or been too close to a tornado and I graduated from the University of Oklahoma, a school in the heart of the Tornado Belt. My wife has seen two tornadoes. I also have a friend, Dave Morris, who is a weather officer in the U.S. Air Force Reserves 920th Weather Reconnaissance Group, Keesler Air Force Base, Mississippi, and he regularly flies into the eye of hurricanes making scientific measurements. He says, "A hurricane flight is often more than just a bumpy ride. It can be a slam bang, stomach churning, spine jarring, heaving, yawing, pounding nightmare of a ride with pilots struggling at the controls and meteorologists straining to read their instruments." (Al Peterlin)
Q: Do problems with air pollution, the ozone layer, and the greenhouse effect have any influence on the frequency and/or severity of hurricanes?
A: As far as I know, there have been no studies that relate hurricane activity to ozone depletion. However, air pollution and the greenhouse effect are related since industrial pollutions can increase the greenhouse effect. An increase in the greenhouse effect is theorized to lead to global warming. And, as atmospheric temperatures warmed, then so would the ocean waters.
Warm ocean waters fuel hurricanes, and it has been theorized that warmer ocean waters would lead to more intense hurricanes. Warmer waters might also increase the length of the hurricane season, which could mean more storms, but the difference would not likely be large.
I cannot say for sure that global warming is occurring because I don't think we have the data to support it yet. It is interesting to note, though, that in an average hurricane season the Atlantic will see two hurricanes reach 115 m.p.h. sustained-wind speeds. That classifies them as "intense hurricanes." In 1996, we had four or five intense hurricanes (Bertha, Fran, Hortense, Isadore). For the number of total hurricanes that have formed, this is a high percentage and very unusual! (Barbara McNaught Watson)
Q: Is New Jersey currently experiencing more hurricanes than in the past?
A: Indeed, it seems like more hurricanes are occurring. Actually, hurricanes in the Atlantic basin — where New Jersey is located — follow a 22- to 23-year cycle. The 1970s and the 1980s were a period of low activity. We have now moved into an active cycle. 1995 was close to a record for the number of storms in the Atlantic. This year we have not had as many storms, but more hurricanes have threatened the East Coast and New Jersey. Back in the 1950s and 60s, tropical cyclone activity was very high and many affected the mid-Atlantic region. In 1955, Hurricane Connie and Hurricane Diane struck just five days apart! The rain from these storms and a third storm led to a record flood on the Delaware River. (Barbara McNaught Watson)
Q: Have you ever personally experienced a hurricane?
A: I have never been in a full-blown hurricane, but I have experienced the "remnants" of hurricanes, which is what most of us experience. When a hurricane moves inland, it begins to weaken. Once the storm's wind falls to less than 75 m.p.h., it is no longer called a hurricane. However, it can still do a lot of damage from heavy rains which, cause flooding and form tornadoes. So hurricanes can produce tornadoes!
When I was 11 years old, the remnants of Hurricane Agnes struck Pennsylvania. I lived in a small town north of Philadelphia. I remember going to bed listening to the sound of the rain hitting the tin porch roof outside my window. I had never heard it rain so hard. I could also hear water rushing down the creek near our house. When I woke up the next morning, the rain had stopped and the sun was out, but I could still hear the roar of the creek. It was flooding the town and water was in some homes and stores. We lived up on a hill so we were not flooded.
Over the next few days we watched the television news reports of the devastating floods. Some people lost their homes and many more were damaged. My mother collected up clothes and blankets that we could donate. Then we gathered with others and took a bus to one of the cities that had bad flooding. The water was gone now and the river was back to its normal level, but it left behind mud and debris.
We were organized into work groups and went out to people's homes to help them clean up and begin repairs. One house we went to was three miles from the river and yet the water had risen to five feet in their home! I will never forget the sound of the hard rain, the roar of the creek, the vision of my town being flooded and the television pictures. I will always feel good about what we did to help those who needed it after the flood. (Barbara McNaught Watson)