ON-AIR FAQ for LFSTORM Program 1
THE "WHO, WHAT, WHERE, WHEN AND WHY" OF WEATHER


El Niño and La Niña   Hurricanes   Meteorology (career)  NASA Weather  Tornadoes
Tropical Rainfall Measuring Mission
   Weather   Winter Storms

EL NIÑO AND LA NIÑA

QUESTION:
What effects does El Niño have on the world other than higher temperatures in some areas? Bart, Charleston Middle School, Charleston, IL
ANSWER:
Dear Bart,
El Niño has many other effects other than those on temperature. For instance, during an El Niño there are noticeably fewer hurricanes in the Atlantic Ocean. In some areas of the southeast United States, there are more tornadoes during El Niño conditions. Drought conditions occur in portions of Asia with floods in other countries of the world.
Some of these events would happen even without El Niño, but during El Niño there are more extreme weather conditions.
EXPERT:
Jim Lushine
National Weather Service

QUESTION:
Did La Nina cause the late typhoon season and the large number of typhoons hitting northern Japan this year?
ANSWER:
That's a good question! La Niña does have an effect on the number of hurricanes in the Atlantic Ocean, by allowing more hurricanes to form than under other conditions. Presumably, there are effects caused by La Niña on typhoon formation as well. La Niña also plays a part in the track that hurricanes take, and likewise it may have had an effect on the track of the western Pacific typhoons.
EXPERT:
Jim Lushine
National Weather Service

QUESTION:
The Navy meteorology group here in Misawa, Aomori, Japan, told us the temperature in the Sea of Japan is almost one degree warmer than normal this winter. Is this due to global warming or La Niña? Is this why we had a late winter?
ANSWER:
I can't be sure. Globally, air temperatures have risen in recent years and this would likely lead to a rise in sea surface temperatures. The direct effects on water temperature from La Niña are confined mainly to the tropical Pacific Ocean, which would be south of the Sea of Japan. The warmer waters may have contributed to the larger number of typhoons that affected Japan this past year and certainly could have had a modifying impact on your winter weather.
EXPERT:
Jim Lushine
National Weather Service

QUESTION:
What caused El Niño and the warm temperatures that came with it and why did it happen? Richie, Charleston Middle School, Charleston, IL
ANSWER:
El Niño is caused by a recurring cycle in which the sea surface temperatures in the tropical Pacific Ocean periodically warm up and then cool down. No one is exactly sure how this works, but it begins with a change in the air pressure which leads to a change in wind direction which eventually causes the change in water temperature. Once the water is heated, it causes the air above it to speed up which causes changes in the weather such as the warm temperatures in Illinois. After a while, the change in weather pattern, makes the water temperature go down and the El Niño ends. El Niño occurs every 3 to 5 years, and are frequently followed by the opposite effect called La Niña. La Niña also causes changes in the weather but not as drastic as El Niño.
EXPERT:
Jim Lushine
National Weather Service

QUESTION:
The Navy meteorology group here in Misawa, Aomori, Japan, told us the temperature in the Sea of Japan is almost one degree warmer than normal this winter. Is this due to global warming or La Niña? Is this why we had a late winter?
ANSWER:
I can not say for sure either way and I don't think any one else could either. But, with that said it is most likely caused by an oscillation in the ocean rather than global warming. There are at least three oscillations that I am aware of but let me refer you to a WEB sight "topex-www.jpl.noaa.gov/elnino/elnino.html". You will find information about the oscillations that occur. Mel...
EXPERT:
Mel Nordquist
National Weather Service

HURRICANES

QUESTION:
How are you able to fly an airplane through a hurricane?
ANSWER:
It has to be a very strong airplane with very special (experienced) pilots. We also fly through well above the ground were the turbulence (sudden movement of the air) is less. The air is moving faster at these levels but it is less turbulent. We also know were the weak spots are with the radar on the plain.

QUESTION:
What things do air reconnaissance fliers look for when they fly into the path of a hurricane? Wyatt, Charleston Middle School, Charleston, IL
ANSWER:
Greetings from Miami!
The reconnaissance aircraft look for a few different things when they fly into hurricanes. The most important things to know are the location of the hurricane, its intensity, and its size. This information is needed to forecast where the hurricane is going, when it will arrive there, how strong it will be, and how large an area the storm will affect.
To do this, we fly what are called "legs," or straight-lines from one end of the storm to the other through the center or eye of the storm. We start where we first see the strong winds of the hurricane, sometimes as little as 40 miles from the eye, and sometimes as big as 200 miles from the eye. As we go toward the eye, the winds increase until we get to the area just outside the eye, which we call the eyewall. This has the fastest winds, and here we find out how intense the storm is. When we get into the eye, the winds die down, and sometimes the sun or the stars come out. We find the exact center of the storm, which gives us the location. Then we fly through the eyewall on the other side of the eye, and then continue until we get past the outer edge of the storm.
After that, we fly with the wind (counterclockwise around the storm), and then make another pass through the eye, or leg, at a right angle to the first. We continue to do that until the mission ends. For example, we may start to the west of the storm, and fly toward the east through the eye and to the other side. Then we fly around the storm to the north, and then fly south through the eye and to the other side. By passing through the eye many times and from different directions, we can get an idea of how strong and large different sides of the storm are, whether the storm is strengthening or not, and where and how fast it is moving. This information is sent from the airplanes to the forecasters at the National Hurricane Center who issue the forecasts based on these data.
The way we find the eye is interesting. Since the winds flow around the eye in a counterclockwise circle, we need to fly at a right angle to the wind, with the wind blowing from the left of the airplane toward the right. We also have a Doppler Radar on the planes, much like the ones you see on your local weather report on TV. With the radar, we can see the eye from about 100 miles away, and fly toward the eye on the radar. The aircraft is equipped with all sorts of instruments that measure wind speeds and pressure, which tell us how intense the storm is.
EXPERT:
Sim Aberson
NOAA/AOML, Hurricane Research Division

QUESTION:
Why are hurricanes named and tornadoes aren't? Jerad, Charleston Middle School, Charleston, IL
ANSWER:
Hurricanes last for a long time. The longest-lived hurricane was Hurricane John in the Eastern Pacific Ocean in 1994. It lasted for a full month. Because they last for a long time, we can see that a hurricane currently exists, track it, and try to forecast where it is going to go. People affected by hurricanes usually have been warned a day before the storm that it will come, and have that time to prepare for it. However, sometimes two hurricanes are happening at the same time, there might be confusion between the two storms. Naming the hurricanes can help end this confusion.
Tornadoes, on the other hand, live only for a few minutes, and there is very little warning or preparation time if a tornado hits. Therefore, naming the tornadoes is not important, since people do not follow them for a long time and there is rarely confusion between different tornadoes. Sometimes, big tornadoes are named for the place they struck, so that, after the fact, we can talk about particularly important tornadoes and not be confused with other tornadoes.
EXPERT:
Sim Aberson
NOAA/AOML, Hurricane Research Division

QUESTION:
Are there any differences between hurricanes, typhoons, and cyclones? Mike, Charleston Middle School, Charleston, IL
ANSWER:
Mike:
Good question.
Hurricanes, typhoons and cyclones are the same type of storm system, a tropical cyclone which forms in the tropics. Hurricanes are tropical cyclones in the Atlantic Ocean and the Pacific Ocean east of the dateline, typhoons are tropical cyclones in the Pacific Ocean west of the dateline and cyclones are tropical cyclones in the Indian Ocean.
EXPERT:
Wayne Presnell
National Weather Service

QUESTION:
If you live deep down south along a coastline, like Florida or S. California, what are the chances of your home being damaged during hurricane season? Amanda, Charleston Middle School, Charleston, IL
ANSWER:
In the Florida Keys the chance is once in every eleven years. However, in the last two hurricane seasons my house was damaged by Hurricane George, Irene, and Tropical Storm Mitch. The number of hurricanes from year to year is quite variable. As advances in science are being made we have discovered that global weather patterns affect the number of hurricanes.
EXPERT:
Bobby McDaniel
National Weather Service

QUESTION:
How fast do they fly when they "punch the eye wall" of a hurricane? Dustin, Charleston Middle School, Charleston, IL
ANSWER:
This is an interesting question and unfortunately, I can not give you an exact speed, as I don't know. However, the optimum cruise speed of a hurricane hunter is near 300 mph and I imagine it speeds up when "punching" through the eyewall. The aircraft slows down quite a bit when they release the dropsondes. Dropsondes are instruments which measure different elements such as temperature, pressure, wind speed and direction and relative humidity, of the atmosphere at different levels during its descent to the ocean. This data is sent back to the National Hurricane Center and is very important to hurricane forecasters. The hurricane hunter aircraft enters the eyewall around a level of 10,000 feet above sea level.
EXPERT:
Wayne Presnell
National Weather Service

QUESTION:
Last year, my third graders wanted to know: We live in southeastern Georgia, in the barrier islands area. Every time a hurricane gets near us, it almost always looks like it will hit, but spins away at the last minute. Our ocean water is very brown from the tannin and detritus from the Altamaha and the swamps and marshes. Is it because the detritus hold more warmth in the water in our area that the hurricanes spin off because there is more heat rising up from the detritus filled rivers that empty into the ocean?
ANSWER:
Hurricanes are steered by the surrounding environmental winds. (Think of it like a leaf being pushed around by the eddies in a stream.) The ocean waters have no effect on where the hurricanes go, though the temperature does impact how strong it can get (the warmer the ocean, the more intense the hurricane can become).
EXPERT:
Chris Landsea
National Weather Service

QUESTION:
How far inland can a hurricane travel before wearing itself out? Abbie, Charleston Middle School, Charleston, IL
ANSWER:
Hurricanes weaken after making landfall because they lack the warm, moist air from the ocean that supplies their source of energy. Typically, the winds start dying off soon after landfall, so that within a day even a major hurricane has decayed to just a tropical storm. Since the weakening is more a factor of time than distance, a fast moving hurricane can bring strong winds further inland than can a hurricane that is moving slowly. Typically, the farthest inland one would expect to experience hurricane winds would be a couple hundred miles from the coast.
EXPERT:
Chris Landsea
National Weather Service

QUESTION:
You've presented the cause of hurricanes well and thoroughly but I'd like some discussion on solutions.
Besides better predictions, I'd like to hear some discussion on eliminating the threat posed by hurricanes altogether, by eliminating the hurricane. Is there any research being done in this area? If not, why not? Now that we understand how hurricanes form and sustain themselves on a basic level, don't we have the technological power and know how to interrupt a hurricane's formation?
thank you in advance for your reply,
Just dreamin,
gary
ANSWER:
Weather modification has been extensively studied in relation to hurricanes starting during World War II and extending even to today. There have been a number of research projects including cloud seeding to make the hurricane rain itself out, or efforts to limit evaporation of water from the warm oceans. Unfortunately, none of these have worked for various reasons. Cloud seeding did not have any appreciable impact on hurricanes. Efforts to limit evaporation have environmental concerns, since they usually involve adding certain chemicals to the ocean surface.
Other techniques have involved using hydrogen bombs to disrupt the circulation. However, this would unleash large amounts of radiation into the atmosphere that may be more harmful than the hurricane itself. Further, the amount of energy expended in a hurricane is many times the amount of energy of a hydrogen bomb every second. Therefore, current bombs will likely have no impact on the tropical cyclone.
Then there are the simple philosophical concerns. Hurricanes have a beneficial impact on the environment. Most ecosystems in hurricane regions rely on the storms to prosper. Eliminating hurricanes may irrevocably harm ecosystems such as Florida Bay and the Everglades.
We live in nature. I do not believe that we will ever control nature. We will always have to live with hurricanes, tornadoes, earthquakes, volcanoes, etc. The best we can do is warn and prepare for such events. Hurricanes are important in the circulation of the atmosphere. Removing this important component may have more drastic effects to the earth's climate than the beneficial impacts of stopping hurricanes from happening at all.
EXPERT:
Sim Aberson
NOAA/AOML, Hurricane Research Division

QUESTION:
What was the name of the hurricane that meteorologists have collected data from? Mrs. Dexter’s Seventh Grade Class, Hydesville School, Hydesville, CA.
ANSWER:
Well the one that is shown in the "Live from the Storm" video is from Hurricane Dennis that occurred in late August, early September of last year (1999). We collect data every hurricane season. We fly into hurricanes every year. We have been collecting data from hurricanes since the 1950s.
EXPERT:
Shirley Murillo
NOAA/AOML, Hurricane Research Division

QUESTION:
You've presented the cause of hurricanes well and thoroughly but I'd like some discussion on solutions. Besides better predictions, I'd like to hear some discussion on eliminating the threat posed by hurricanes altogether, by eliminating the hurricane. Is there any research being done in this area? If not, why not? Now that we understand how hurricanes form and sustain themselves on a basic level, don't we have the technological power and know how to interrupt a hurricane's formation? thank you in advance for your reply, Just dreamin, gary
ANSWER:
Actually for a couple decades NOAA and its predecessor tried to weaken hurricanes by dropping silver iodide - a substance that serves as a effective ice nuclei - into the rainbands of the storms. The idea was that the silver iodide would enhance the thunderstorms of the rainband by causing the supercooled water to freeze, thus liberating the latent heat of fusion and helping the rainband to grow at the expense of the eyewall. With a weakened convergence to the eyewall, the strong inner core winds would also weaken quite a bit. Neat idea, but it, in the end, had a fatal flaw: there just isn't much supercooled water available in hurricane convection - the buoyancy is fairly small and the updrafts correspondingly small compared to the type one would observe in mid-latitude continental super or multicells. The few times that they did seed and saw a reduction in intensity was undoubtedly due to what is now called "concentric eyewall cycles".

Concentric eyewall cycles naturally occur in intense tropical cyclones (wind > 50 m/s or 100 kt). As tropical cyclones reach this threshold of intensity, they usually - but not always - have an eyewall and radius of maximum winds that contracts to a very small size, around 10 to 25 km. At this point, some of the outer rainbands may organize into an outer ring of thunderstorms that slowly moves inward and robs the inner eyewall of its needed moisture and momentum. During this phase, the tropical cyclone is weakening (i.e. the maximum winds die off a bit and the central pressure goes up). Eventually the outer eyewall replaces the inner one completely and the storm can be the same intensity as it was previously or, in some cases, even stronger. A concentric eyewall cycle occurred in Hurricane Andrew (1992) before landfall near Miami: a strong intensity was reached, an outer eyewall formed, this contracted in concert with a pronounced weakening of the storm, and as the outer eyewall completely replaced the original one the hurricane reintensified.

Thus nature accomplishes what NOAA had hoped to do artificially. No wonder that the first few experiments were thought to be successes. As for the other ideas, there has been some experimental work in trying to develop a liquid that when placed over the ocean surface would prevent evaporation from occurring. If this worked in the tropical cyclone environment, it would probably have a detrimental effect on the intensity of the storm as it needs huge amounts of oceanic evaporation to continue to maintain its intensity (Simpson and Simpson 1966). However, finding a substance that would be able to stay together in the rough seas of a tropical cyclone proved to be the downfall of this idea.

There was also suggested about 20 years ago (Gray et al. 1976) that the use of carbon black (or soot) might be a good way to modify tropical cyclones. The idea was that one could burn a large quantity of a heavy petroleum to produce vast numbers of carbon black particles that would be released on the edges of the tropical cyclone in the boundary layer. These carbon black aerosols would produce a tremendous heat source simply by absorbing the solar radiation and transferring the heat directly to the atmosphere. This would provide for the initiation of thunderstorm activity outside of the tropical cyclone core and, similarly to STORMFURY, weaken the eyewall convection. This suggestion has never been carried out in real- life.

Lastly, there always appears ideas during the hurricane season that one should simply use nuclear weapons to try and destroy the storms. Apart from the concern that this might not even alter the storm, this approach neglects the problem that the released radiation would fairly quickly move with the tradewinds to over land. Needless to say, this is not a good idea.

< Start Soap Box >

Perhaps the best solution is not to try to alter or destroy the tropical cyclones, but just learn to co-exist better with them. Since we know that coastal regions are vulnerable to the storms, enforce building codes that can have houses stand up to the force of the tropical cyclones. Also the people that choose to live in these locations should willing to shoulder a fair portion of the costs in terms of property insurance - not exorbitant rates, but ones which truly reflect the risk of living in a vulnerable region.

( End Soap Box )
EXPERT:
Chris Landsea
NOAA AOML/Hurricane Research Division

METEOROLOGY (CAREER)

QUESTION:
What kind of courses in college should you take if you want to be a meteorologist and how many years of school are required? Amanda, Charleston Middle School, Charleston, IL
ANSWER:
You can get a degree in meteorology at the Bachelors level (4 years of college) that will enable you to get a job working as an observer or forecaster at a private weather forecasting firm or the National Weather service. If you are interested in why things are the way they are and you wanted to do meteorological research you would need to get a Masters degree (2 more years of school) or a Doctoral degree (3-5 more years). Either degree would get you a job working at a research laboratory or university, but at the Doctoral level you would be expected to generate your own research topics and funds to support them. Besides taking courses in meteorology you will need a good background in mathematics and physics. You will need to take math courses at least through calculus and linear algebra and at least 1 full year of physics and thermodynamics.
EXPERT:
Frank Marks
NOAA/AOML, Hurricane Research Division

QUESTION:
What makes someone want to be a meteorologist and what skills are required? Alex, Charleston Middle School, Charleston, IL
ANSWER:
For me it just happened. Ever since I was a kid, I've always enjoyed science. I like discovering and learning new things. I became curious about the weather especially hurricanes since I live in Miami, Florida. What made want to become a meteorologist is my love for the weather. I enjoy coming to work and investigating hurricanes but it wasn't an easy path getting to where I am today. If you are thinking of becoming one make sure you have strong math and science skills. I took many math and science courses, physics in particular. Writing is also very important. Half of my time is spent writing and publishing articles on my scientific findings. Four years of college is the minimum requirement. Most meteorologist go for advanced college degrees like a master's degree and a doctorate's degree.
EXPERT:
Shirley Murillo
NOAA/AOML, Hurricane Research Division

QUESTION:
How do the financial rewards of being a meteorologist compare with other career choices? Sam, Charleston Middle School, Charleston, IL
ANSWER:
Let me put it this way, if you want to be rich, do something else. That said, I wouldn't trade my job for any other one I could think of. The pay is not paid to do something I love to do. It is like someone paying me to do my hobby. I have traveled around the world at least twice in my 30 years as a meteorologist. I have worked on experiments in Africa, SE Asia, Australia, Mexico, and the S Pacific Islands. I have experienced things very human beings have ever experienced, like flying into a hurricane. What price can you put on those experiences? I view myself as very richly rewarded for what I do and no amount of monetary reward would make me change my career. There is more to life than making money. You need to find a career that you enjoy and grow into as well. I have found meteorology to satisfy that need for me.
EXPERT:
Frank Marks
NOAA/AOML, Hurricane Research Division

NASA WEATHER

QUESTION:
What is the best instrument to use to predict the most accurate forecast of the weather?
ANSWER:
Meteorologists or forecasters tend to use a variety of instruments including ground-based in-situ measurements and remote sensing measurements. Instruments like thermometers and wind vanes are "in situ" because they are directly measuring a parameter like temperature or wind direction. Remote sensing instruments like satellite cameras or radar or your own eye, make measurements from a distance.
However, if I had one instrument available for forecasting changes in the weather, I would choose a barometer. A barometer measures air pressure or how much the atmosphere above you weighs. Generally, changes in air pressure are good indicators of weather changes. For example, a falling barometric pressure usually indicates the approach of a Low or lower pressure, which is generally associated with rainy or stormy weather.
EXPERT:
Marshall Shepherd
NASA-Goddard Space Flight Center

TORNADOES

QUESTION:
Have you ever been with a group of people that chase tornadoes and what did you learn?
ANSWER:
Yes. Chasing, DONE SAFELY, can contribute to the meteorologists knowledge of how the atmosphere acts when severe weather can develop. In science, do you learn more when you are taught by the teacher alone? Or when you can do experiments along with the teachings from your teacher? I'd say when you can do both, you learn more. Same with studying severe thunderstorms and tornadoes. Each time one goes to see storms and tornadoes develop, one learns more of how they form to study why they form.
EXPERT:
Daniel McCarthy
Storm Prediction Center
National Severe Storms Laboratory
Norman, OK

QUESTION:
In the movie Twister a cow was picked up by a tornado. Could such an animal live through this experience? What is the heaviest object a tornado could carry? Jenna, Charleston Middle School, Charleston, IL
ANSWER:
The "cow" angle in the movie "Twister" was based on an actual account by a storm chaser! Odds are against the cow. It is hard to answer your question on the heaviest object carried by a tornado. I know from last year's Oklahoma City tornado cars, trucks, even those big Ford Expeditions were picked up and carried a couple of miles by the tornado! What does a big tornado pick up? Whatever it wants!
EXPERT:
Daniel McCarthy
Storm Prediction Center
National Severe Storms Laboratory
Norman, OK

QUESTION:
How has storm chasing contributed to what we know about tornadoes?
ANSWER:
Chasing for tornadoes, when done safely, helps severe storm scientists understand more what goes on in the atmosphere when conditions are favorable. We see can see and feel the low level flow change into inflow when the circulation develops prior to the tornado. The more we study and analyze the environment near the storm prior to the tornado, the closer we get to understanding the processes involved.
EXPERT:
Daniel McCarthy
Storm Prediction Center
National Severe Storms Laboratory
Norman, OK

QUESTION:
Why are IL, KA, OK, MO, and IN the states that are more prone to having tornadoes then other states? Lauren, Charleston Middle School, Charleston, IL
ANSWER:
Actually, data from the last 49 years has shown that the States more susceptible to tornadoes are Texas, Oklahoma, Kansas, and Nebraska. Tornadoes can and have occurred in every state of the 48 contiguous states. Over the past few years, their occurrence has increased across Illinois, and Indiana as more people are available to observe the tornado's occurrence, and cold/warm front boundaries become stalled across these areas. Mostly, we are able to direct spotters towards areas where the Doppler Radar is detecting mesocyclone circulations to observe development of tornadoes.
EXPERT:
Daniel McCarthy
Storm Prediction Center
National Severe Storms Laboratory
Norman, OK

QUESTION:
Why do tornadoes mainly occur in the Midwest in the spring? Ryan, Charleston Middle School, Charleston, IL
ANSWER:
The U.S. has a very unique set up that produces tornadoes in the Midwest. First is the long north/south chain of the Rocky Mountains. When southerly winds flow northward bringing warmer, more humid air from the latitudes of the Gulf of Mexico, the moisture can not move westward as it hits the "wall" of the Rockies. Then, as weather systems bring cooler air from the polar latitudes it creates a battle front where the warm, moist air is lifted rapidly to create storms.
In short, it's the Rocky Mountains and the Gulf of Mexico.
EXPERT:
Daniel McCarthy
Storm Prediction Center
National Severe Storms Laboratory
Norman, OK

QUESTION:
What is the average level of humidity in a tornado? 7th. graders, Hydesville School
ANSWER:
A tornado is a violently rotating column of air in contact with the ground. Frequently, we see a funnel cloud associated with the tornado. In the funnel cloud, the relative humidity is approximately 100%. In parts of the tornado not made visible by the funnel cloud, the relative humidity is still probably very high.
EXPERT:
Harold Brooks
National Severe Storms Laboratory
Norman, OK

QUESTION:
How hot or cold can a tornado be? Mrs. Dexter’s Sixth grade class, Hydesville School, Hydesville CA.
ANSWER:
We don't have direct measurements of the temperature inside tornadoes. It is likely, however, that it is a little cooler (maybe a few degrees) than the environmental air outside of the thunderstorm that the tornado forms form.
EXPERT:
Harold Brooks
National Severe Storms Laboratory
Norman, OK

QUESTION:
How does a tornado stop turning? Mrs. Dexter’s Seventh Grade Class, Hydesville School, Hydesville, CA.
ANSWER:
Let's start with a simple conceptual model of one way to make a tornado. (There may be other ways, but this one has a relatively simple answer.) The strongest tornadoes form from a kind of thunderstorm called a supercell. Supercells have updrafts (winds going up) that rotate slowly through the depth of the storm (say, from a few thousand feet off the ground to ~50,000 ft). One of the things the rotation does is to wrap rain around the updraft back around to the right rear of the updraft, if you were flying along with it.
EXPERT:
Harold Brooks
National Severe Storms Laboratory
Norman, OK

QUESTION:
Is there a chance in the near future that there will be a way to break up or destroy a tornado before it destroys lives? Katie, Charleston Middle School, Charleston, IL
ANSWER:
No. I don't think there is much of a chance that at any time in the future we will be able to do that. Even though the tornado is only a small part of the parent thunderstorm, the energy associated with it (on the order of the release of atomic bombs) is huge. It's not clear that anything that would be large enough to destroy the tornado wouldn't have drastic, unintended consequences.
EXPERT:
Harold Brooks
National Severe Storms Laboratory
Norman, OK

QUESTION:
Is there any location on Earth where tornadoes cannot occur? Matt, Charleston Middle School, Charleston, IL
ANSWER:
Tornadoes have not been observed on Antarctica, presumably because there aren't many thunderstorms.
EXPERT:
Harold Brooks
National Severe Storms Laboratory
Norman, OK

QUESTION:
How do you measure the wind speed inside a tornado? Cassandra, Charleston Middle School, Charleston, IL
ANSWER:
We really don't do that. There have been a few direct hits on anemometers by weak tornadoes, but the anemometers tend to break when things get really interesting. People use mobile Doppler radar to get estimates of the winds in a tornado without having to get inside the tornado. Doppler radar works by measuring the slight change in 'pitch' associated with raindrops moving towards or away from the radar (just like the pitch of a railroad whistle changes as the train approaches or leaves you). By measuring the change in pitch, we can estimate how fast the raindrops are moving.
EXPERT:
Harold Brooks
National Severe Storms Laboratory
Norman, OK

QUESTION:
Why does the sky often turn green before a tornado? Tammy, Charleston Middle School, Charleston, IL
ANSWER:
We don't really know. Every time I've seen the green sky, it's been associated with hail. Since most tornadic storms also produce hail, it's likely we're seeing something associated with the hail. (I've also seen the green color with non-tornadic hailstorms.) Beyond that, it's hard to say. There has been research into trying to identify why hail makes the storm look green, but it's not clear what the answer is.
EXPERT:
Harold Brooks
National Severe Storms Laboratory
Norman, OK

QUESTION:
Why do tornadoes form the shape they do? Ashley, Charleston Middle School, Charleston, IL
ANSWER:
At one level, the answer to this question is "We don't have any idea." In general, tornadoes form their shape because of friction at the ground and the strong vertical velocities just about the ground.
I think what you're really asking is why funnel clouds form the shape that they do. A tornado is a violently rotating column of air in contact with the ground. (Note that that says nothing about clouds.) The funnel cloud is frequently a visible manifestation of the tornado. Funnel clouds become visible when the water vapor content becomes greater than the saturation vapor pressure of the atmosphere at that temperature and pressure. (When that happens, the relative humidity is 100%.) Pressure and temperature in the atmosphere generally get lower as you go up, so that putting in a constant amount of water vapor will saturate a larger amount of air as you go up. In the lowest parts of the tornado (say 1-3 km), the absolute amount of water vapor is probably close to constant with height. Since the pressure and temperature of the environment are going down with height, the area that is saturated will get larger and larger as you go up, giving a funnel-shaped appearance to the cloud.
EXPERT:
Harold Brooks
National Severe Storms Laboratory
Norman, OK

TROPICAL RAINFALL MEASURING MISSION

QUESTION:
How can the TRMM measure rainfall? Emily, grade 7
ANSWER:
You can get lots of information about this question by clicking on the links at
http://trmm.gsfc.nasa.gov/instrumentfacts.html
But let me summarize:
There are three instruments on TRMM specifically designed to measure rainfall: 1) Precipitation radar (PR), 2) TRMM Microwave Imager (TMI) and 3) the Visible and Infrared Scanner (VIRS). These three instruments measure rain in three different ways.
PR: The Precipitation Radar sends a microwave signal down from the satellite. The signal bounces off the clouds, rain and land below and returns to TRMM in orbit. By measuring the time it takes for the signal to come back to the satellite and how strong the signal is, we can calculate how far away the echo came from and how much rain is falling. The calculations for how much rain is falling are not simple! They depend on how strong the echo is, how much the signal has been absorbed or reflected by higher layers in the atmosphere and on the size of the raindrops. Different types of rainfall have different-sized raindrops and that needs to be accounted for in the calculations.
TMI: The TRMM Microwave Imager does NOT send out a signal like the radar does. Instead, TMI is measuring the microwaves that are naturally being emitted by the Earth. Clouds and rainfall in the atmosphere emit different types and amounts of radiation than the land and oceans do. These differences are used to calculate the amount of rainfall. These calculations are more accurate over the oceans because the oceans appear very dim (or cold) and the rainfall appears brighter (or warmer). The land brightness (or temperature) is very close to that of the rainfall and is also more variable than the signal over the oceans. So it is both more difficult to separate the rain from the land and more difficult to measure accurately how much rain falls over land.
VIRS is included largely to be able to compare TRMM measurements with those collected by other weather satellites, especially the GOES (Geostationary Orbit Environmental Satellite) which you see almost every day on the TV weather reports. The infrared sensors again measure the temperature of the features below the satellite. High clouds are cold clouds and are easily identified. High clouds are often the source of rainfall (but not always)! So long-term measurements of infrared (like monthly averages) are a good predictor of monthly rainfall because any place that has a lot of high clouds will have a lot of rain. But a single infrared image doesn't do as well, because tall cold clouds are not enough to determine whether they are indeed producing rainfall.
EXPERT:
Alan Nelson
NASA Goddard Space Flight Center

WEATHER

QUESTION:
What is the hottest and coldest temperatures ever recorded? Mrs. Dexter’s Seventh Grade Class, Hydesville School, Hydesville, CA.
ANSWER:
The hottest temperature ever recorded on earth was in the country of Libya, in the Sahara Desert in Africa, where the temperature reached 136.4F. The hottest temperature in the United States was recorded in Death Valley in California with a temperature of 134F.
The coldest temperature on earth was recorded in Antarctica with a low of -126.9F. The coldest temperature in the United States was -80F in Alaska. Thanks for your good question!
EXPERT:
Jim Lushine
National Weather Service

QUESTION:
Can air pressure be affected by wind? Mrs. Dexter’s Seventh Grade Class, Hydesville School, Hydesville, CA.
ANSWER:
It is differences in air pressure, which is the weight of air above us, that causes wind in the first place. Air in a column about our head, on average weighs about 15 kg. You can feel that weight all the time. If you want to do an experiment to document that air has weight wave a notepad through the air. What do you feel? The pad moved the air and you felt it. That is how wind comes about. The weight or pressure of the air is not the same everywhere. In some places there is more air than others. Regions that have more air with more weight are called high pressure regions, and regions that have less weight or pressure of the air are called low pressure regions. Now if there is more air in one place and less in others what do you think occurs. The excess air in the high pressure region moves toward the low pressure region. That air movement is WIND! The bigger the difference in pressure or weight between the two regions the faster the wind will blow. Hurricanes are regions of unusually low pressure hence the fast winds we see in hurricanes.
EXPERT:
Frank Marks
NOAA/AOML, Hurricane Research Division

QUESTION:
What is the best instrument to use to predict the most accurate forecast of the weather? Mrs Dexter’s Sixth grade class, Hydesville School, Hydesville School, CA.
ANSWER:
The network computer system we use to receive weather data is the most used instrument. Our system is called the Advanced Weather Interactive Processing System (AWIPS). It integrates all data such as satellite, radar, and computer model data.
EXPERT:
Bobby McDaniel
National Weather Service

QUESTION:
Are the heavy rains that flooded Mozambique considered monsoons? Tonya, grade 6
ANSWER:
It's a combination of both monsoons and the typhoon the made landfall in that area just a couple of weeks ago. During a La Nina event (which is what we are in now) the South African coast is exposed to monsoons.
EXPERT:
Shirley Murillo
NOAA/AOML, Hurricane Research Division

QUESTION:
How does a change in air pressure contribute to building a storm? Thanks, Kevin
ANSWER:
It goes with the basic knowledge that warm air rises and cold air sinks. Pressure is a measurement of the amount of atmosphere either sinking toward the earth or rising away from the earth. In High pressure, the value is higher because air is sinking onto the surface. Pressure drops as air rises vertically away from the earth. Warm air rises rapidly when a storm forms condensing moisture creating the storm. That's why skies are clear when there's High pressure and stormy in the vicinity of low pressure.
EXPERT:
Daniel McCarthy
Storm Prediction Center
National Severe Storms Laboratory
Norman, OK

QUESTION:
What is the wind chill factor/conversion?
ANSWER:
The wind chill factor is related to the affect evaporation and heat loss have on the body of a person. It is a combination of the affects of temperature and wind on exposed skin. The higher the wind speed the faster heat is carried away and the more effective the chilling of the skin. Hence the term wind chill factor.
EXPERT:
Mel Nordquist
National Weather Service

QUESTION:
How can surface air and air higher up act differently? They are both gases. Why does this happen? Liliy
ANSWER:
This is true, but as one gas with changing densities. Air is thought of as a fluid that surrounds the Earth. Because the Earth rotates, this causes air at different latitudes to circulate either towards the equator and away from the poles. This mixture results in the jet streams that migrate weather systems across different areas of the globe. Also, remember that weather moves west - east in the northern half of the Earth...east - west over the southern half as viewed by us.
EXPERT:
Daniel McCarthy
Storm Prediction Center
National Severe Storms Laboratory
Norman, OK

QUESTION:
Can we predict whether the summer in the Midwest will be warmer or cooler than average? John, Charleston Middle School, Charleston, IL
ANSWER:
John,
There are climate models that attempt to predict seasonal temperatures like "will the Midwest be warmer or cooler than normal. But, it is important to understand that a model is just a scientific "guess" it is not the real world. Models do miss their predictions. The models I'm referring to are run at the National Center for Environmental Prediction (NCEP) on some of the largest and fasts computers on the planet. They are pretty good at predicting if a large area like the Midwest will be warmer or colder than average but they are not perfect, it is just a prediction.
EXPERT:
Mel Nordquist
National Weather Service

QUESTION:
Why does it rain more in the winter then in the summer along the north coast? Mrs. Dexter’s Seventh Grade Class, Hydesville School, Hydesville, CA
ANSWER:
The polar jet stream flows over the Pacific Northwest more predominantly during the winter than the summer. This brings more weather systems into the Northwest more frequently during the winter months.
EXPERT:
Daniel McCarthy
Storm Prediction Center
National Severe Storms Laboratory
Norman, OK

QUESTION:
When was the first thermometer made and how? Mrs. Dexter’s Seventh Grade Class, Hydesville School, Hydesville, CA
ANSWER:
Galileo is credited in inventing the first thermometer in 1593. I do not know how it was made. Thermometers are mostly made of liquid-in-glass tube attached to a graduated scale. The liquid is either mercury (most widely used) or alcohol because of their very cold freezing levels.
EXPERT:
Daniel McCarthy
Storm Prediction Center
National Severe Storms Laboratory
Norman, OK

WINTER STORMS

QUESTION:
Can lightning strike during a winter snowstorm? Andrew, Charleston Middle School, Charleston, IL
ANSWER:
Andrew,
Absolutely. It's uncommon, but it can happen.
1.3% of all thunder reports occur with snow. Less than one percent of all deaths and injuries due to lightning happen during the winter months (December, January, and February). In fact, one of the topics that I research is the conditions under which snow and lightning can occur simultaneously. We found that when the temperature near the earth's surface is warm (say near freezing) and the lower atmosphere is unstable (cools very quickly with height), this increases the chance of lightning occurring with snowstorms.
Good question!
EXPERT:
Dave Schultz
National Severe Storms Laboratory
Norman, OK

QUESTION:
Can animals tell when a storm is coming? Tiffany, Charleston Middle School, Charleston, IL
ANSWER:
It's possible that they can smell the smell associated with rain and thunderstorms, which apparently results from getting dirt wet and the production of ozone by lightning discharges, but I don't know of any evidence that they can tell any better than humans can.
EXPERT:
Harold Brooks
National Severe Storms Laboratory
Norman, OK

QUESTION:
How do the energies in winter storms such as Nor'easters compare with those in hurricanes and tornadoes???
ANSWER:
That's a tough question for several reasons.
First, not all winter storms (Nor'easters are just one type of low pressure system) are the same, just like not all tornadoes or hurricanes are the same and have the same intensity. Therefore, comparing the total energy output over the lifetime of a storm may not be easily calculable.
Personally, I prefer to think of the difference between these storms in terms of (a) the source of the energy for the storm and (b) the size of the storm. Tornadoes are the smallest of the three. They have diameters usually only a few hundred feet across, but sometimes they can be as big as a mile across. The wind speeds are typically 100-200 mph. Compare that to hurricanes which have a diameter of 50 miles or so with maximum wind speeds of 50-100 mph. Finally, low pressure systems have diameters of hundreds to a thousand miles with maximum wind speeds at the surface 10-50 mph. The source of energy in tornadoes is the strong heat at the surface coupled with the release of latent heat during the condensation of water vapor. In hurricanes, it is the release of latent heat that drives the storm. In low pressure systems it is the temperature difference between the tropics and the poles that supplies the energy to the storm. Thanks for asking this question!
EXPERT:
Dave Schultz
National Severe Storms Laboratory
Norman, OK

QUESTION:
Are there any certain patterns for winter storms, like every 4 years as an example? Jon, Charleston Middle School, Charleston, IL
ANSWER:
Jon,
Yes, there are patterns to the climate and as such patterns for winter storms. One of the most familiar annual cycle of storms is the moving of the so called "storm track" north in the summer and south in the winter, in the northern hemisphere. There are longer cycles from a few years to as many as ~20 years. Current research is finding that these cycles are linked to changes in the equatorial sea surface temperatures of the pacific ocean. There is still a great deal of research to be done in this area.
EXPERT:
Mel Nordquist
National Weather Service