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Weather: Top 10 Questions

February 2014

Thanks to meteorologists Vin Crosby (KBOI-TV) and Robyn Heffernan (NOAA) for their answers.

1: How hard is it to predict the weather?

It is very complex to predict the weather. Meteorologists all around the world launch weather balloons twice a day to get information that gets put into computers in Maryland. The math is out of this world to get a weather forecast by the computers. The weather forecast by the computers is not always accurate though, so it's up to the meteorologists, based on their experience, what they know, and their education, to make the best decisions on what the weather will be like. (From Kaitlyn at Liberty Elementary School in Boise)

2: How does the wind start?

Wind is created by temperature differences across the Earth. The Earth tilts, creating our seasons, and the differing amounts of radiation from the sun during the day will warm different parts of the Earth's surface. Parts will be cooler and parts will be warmer. The warming and the cooling cause pressure differences. These pressure differences cause the wind. (From Melanie at Lowell Elementary School in Boise)

3: Why does the weather not just stay the same?

It has to do with many things. When warm air rises and cold air sinks, the air starts moving. At the same time, the Earth is spinning and that adds to air rising and sinking around the globe. These factors cause the air to circulate, which helps move air masses from one area to another. Pressure also adds to this helping to cause the weather to change on a daily basis. Basically, as the sun warms the Earth, the warm air rises during daylight and sinks at night. This, along with the spinning Earth, gives us our seasons. (Devin at Cynthia Mann Elementary School in Boise)

4: Why does the temperature drop when the sun rises in the morning?

The Earth's surface radiates heat all night, allowing cooling. The sun rises and it tries to warm the Earth's surface, but until the sun has been up long enough where the incoming warmth is enough to battle the outgoing radiation from the Earth's surface, temperatures will cool. Once the sun's rays can overcome the radiation leaving, the temperature will warm. The night time lows typically occur in the early morning hours after the sun has already come up. (Miya at Kamiah Elementary School in Kamiah)

5: How do hurricanes happen?

Water temperature is the key factor for hurricane formation. The water temperature has to be 80 degrees or higher in order to have a tropical storm. Then many, many factors come into play. Winds have to be light throughout a large column of air. Then we look at the tropics where the water temperatures warm, putting a lot of moisture and instability in the atmosphere. Thunderstorms start to form and grow bigger and bigger. The pressure lowers, and along with many other factors, causes the hurricane to start spinning. It's like an ice skater who brings his arms in and starts spinning faster and faster. It becomes its own little weather system with wind speeds over 74 miles per hour. The wind speeds during a hurricane can rise to much greater speeds. (Olivia at Lowell Elementary School in Boise)

6: How much trouble can a Category 5 hurricane cause?

Unfortunately, a Category 5 hurricane can cause a lot of trouble. It can cause wind damage with winds in excess of 155 mph that can destroy things. It also brings with it water damage. It releases its own water in the form of rain, but can create a storm surge where the ocean is pushed in toward the land, causing flooding at the same time. The amount and kind of damage depends on the strength of the hurricane and how fast the hurricane is moving. (James at Dalton Elementary School in Dalton Gardens)

7: How far can a hurricane spread?

These storms are so, so massive. Tornadoes can go down one side of the street and wreck it, while the other side of the street will be fine. Hurricanes can be the size of states and cause massive amounts of damage. (Daniel at Dalton Elementary School in Dalton Gardens)

8: What causes hail?

Hail is made up of ice. Water droplets in a cloud that is really high up will freeze. Updrafts and downdrafts in the cloud will cause them to rotate. The stronger the thunderstorm the stronger the updrafts will be, not letting the droplets fall. They will be brought back up into the cloud and every time they go around through the cycle of downdrafts and updrafts, they collect more and more ice. It builds and builds and finally they are too heavy and fall out of the cloud in the form of hail. (Kendrick at Kamiah Elementary School in Kamiah)

9: What does wind chill mean?

Wind chill is the rate of heat loss from the skin. It has to do with the amount of heat lost through the body than a wind chill temperature. There is a formula that we plug into the wind speeds and the temperature that we call the wind chill reading. (Bryce at Liberty Elementary School in Boise)

10: Can we have 100 percent humidity?

Yes we can, and we do. We see 100 percent humidity quite often here in Idaho, especially in the winter when we see fog. 100 percent humidity means that the atmosphere is holding as much moisture as it can hold. When it can't hold anymore, the moisture condenses and becomes water droplets and appears as what we know as fog, which is a cloud on the ground. (Jaxon at Dalton Elementary School in Dalton Gardens)


February 2009

Thanks to Robyn Heffernan, meteorologist, National Weather Service (Boise); and Scott Dorval, meteorologist, KIVI-TV (Boise) for their answers.

1: Where does the weather come from?

Weather takes place in the atmosphere, the layer of air that surrounds Earth. Air is a mixture of gases and tiny suspended particles. The weather is generated by pressure differences across the globe. We have high pressure and low pressure and between the two moving all over the planet, wind is created. The wind moves the air; cold air in certain places and warm air in others. That is how weather begins. (From Mallory in Mrs. Woodall's class at Hayden Meadows in Coeur d'Alene)

2: What kind of clouds are there?

Some basic types of clouds include low-level clouds, mid-level clouds, and upper level clouds. Those cumulus puffy clouds, the ones we like to make pictures out of, those are the lower clouds. They're usually out during fair weather. We can look at the clouds and basically get a general forecast of what might be coming. The really low clouds, the dark layered gray clouds, are stratus clouds. And then you start to move up to altostratus (at a higher level than stratus clouds), and the real thin clouds, those are called cirrus clouds and are made out of ice crystals. Sometimes you will see clouds forming over mountains. Air needs to rise to form a cloud. As the air rises it cools and condenses and makes that cloud form. A mountain is what we call an elevated heat source. The sun doesn't warm the air, it warms the ground or solid objects. The sun shines through the air, warms the ground and that warm air that's touching the ground begins to rise. And it will rise up to a certain point where it condenses and makes the cloud. If you have a mountain, you've now got the land sticking way up into the atmosphere, so the sun just starts to heat the top of the mountain. That air doesn't have to rise as far to form a cloud. Many times, especially in the Summer, you'll see clouds forming over mountaintops first before the valley. (From Bradley in Mrs. Woodall's class at Hayden Meadows in Coeur d'Alene)

3: Why does it rain?

When air warms it rises. As it rises, it cools and condenses. That's when you reach the dew point temperature. We talk about how much humidity is out there. When air cools enough to reach its dew point temperature, it is going to condense and form clouds. If you've got enough moisture in the air, and enough uplift (enough air that is rising and creating clouds), you're going to get a lot of moisture, and it will fall back down as rainfall. So the same moisture that came from the surface up into the air that created the clouds is the same moisture coming down as rain. (From Rachel in Mrs. Hunt's class at Cynthia Mann Elementary in Boise)

4: How does a tornado get started?

We are still learning and understanding exactly how it works with a tornado. First of all you need a thunderstorm in the area. In a thunderstorm the air is rising. It cools and condenses and makes a cloud. With thunderstorms you have rapidly rising air. And then you also need to have some type of circulation. So if you get what we call wind sheer, wind blowing in a direction at one elevation and wind blowing in another direction at another elevation, that can create a circulation, which can get a tornado started. There's a little more to it than that, but that's generally what is happening. We do get tornadoes in Idaho. The mountains don't really stop the tornadoes from forming. There was once a tornado that went up and down a 10,000-foot mountain in Yellowstone National Park, in fact. The mountains aren't necessarily going to protect you, but one element missing in Idaho is a great deal of moisture that would make the thunderstorms stronger. They're much harder to find in Idaho as opposed to the Midwest, and they're very difficult to predict. (From Elizabeth in Mrs. Rice's class at Mill Creek Elementary in Middleton)

5: Can it rain when it's sunny?

You need a cloud for it to rain but certainly you don't need a completely cloud-covered sky to have rain. You can have certain clouds in certain areas creating rain, and it doesn't necessarily have to fall directly under the clouds. With wind and pressure changes, that rain can move a little bit and fall outside of that cloud. You might have pockets of sun right above you and still feel the rain coming down. That rain is coming from a cloud, maybe not directly above you, but it started in a cloud. (From Gabrielle in Mrs. Hunt's class at Cynthia Mann Elementary in Boise)

6: Does lightning shoot up from the ground, or down from the sky?

It is a combination of both. Particles with electricity on the surface start to build up toward the cloud at the same time those same particles come down from the cloud. They meet at the same time; we are getting that lightning strike up from the ground, and down from the clouds at the same time, and meeting in the middle. There is a lot of electricity in the lightning bolt. The average bolt has enough electricity to light a hundred-watt bulb for about two months. Lightning is a buildup of electrical charges at the base of the cloud opposite from what's on the ground. And it's almost like a friction. You're rubbing the atmosphere across the ground and creating this friction. So you have different charges at the top of the cloud and the bottom of the cloud, and the air is a very poor conductor of electricity. The charges will build up from the ground and cloud and finally there's so much, it will then jump from one to the other, as opposed to constantly trying to balance out the electricity. The lightning will form after the charges build up. (From Asia at Mill Creek Elementary in Middleton)

7: How is the weather predicted?

There are a couple of ways to predict the weather. One of those ways is by observation. Observing what is happening now can tell us what could be going on in the future. We have what's called upstream weather. Upstream weather, for us in Idaho, would be weather that's happening in Washington and Oregon for example. We look at those observations to see what's going on there to see what might be headed our way in Idaho. That's one way we can predict the weather. The other way is with computer models. We rely heavily on computer models. They take observations like from weather balloon and similar and those are taken across the whole world at the same time. The outcomes are generated from the computer models as to how this weather will progress from the upstream weather, across the world. (From Kira at Vineyard Christian Home School Co-Op in Boise)

8: What is a tsunami and how is it caused?

A tsunami is not caused by weather. Many times earthquakes occur under the ocean. The earth opens the water, drops it, and comes back out; creating a ripple effect in the ocean, and then it will send that wave, which is not very tall when it's out in the ocean. It's coming very low, and very, very fast, and all that energy is spread out over a wide area. As it gets close to shallow water, that energy begins to build up and the wave will grow and grow and grow. (From Noah in Mrs. Coe's class at Valley View Elementary in Boise)

9: How accurate are long term weather forecasts?

Some months are very difficult to predict. Because we are dealing with an inexact science, there's so much uncertainty involved, we know it's happening right now so we can measure that. But as soon as we start to forecast, the accuracy starts to drop off. A few hours from now, our forecast is really good. The further out we get, however, it starts to drop off. So you have to ask yourself, how far off can we forecast? Can we forecast 25 days out? Well, the forecast isn't going to be extremely accurate 25 days out. In fact, we may get a general idea if we might be above or below average as far as temperature and rain and snow. But the first day is very accurate. Tomorrow and the next day is not bad, it starts to drop off a little bit. It's getting better all the time as we improve our technology. Factors that influence that accuracy are going to be the weather pattern that we are in. Certain weather patterns are more predictable than others. Certain times of the year are more predictable. As we have the transition seasons, like the spring and fall, those are trickier because we're changing from more of a stagnant time, its cold all the time. As summertime comes on we are experiencing more volatile weather. The accuracy will again drop off. Knowing where the jet stream is can be pretty important (and, of course, how it's behaving). Certain times of the year there are computer models that will look at that model of that jet stream and where it's supposed to go. We can look at different models and sometimes they don't agree or none of them agree. When that happens, we call it a low confidence forecast, because nobody is sure. Maybe the weather pattern is undergoing a change. But we want to know where that jet stream is going to be because that's going to bring the storms in our direction. (From Molly, a home school student with Idaho Virtual Academy, in Emmett)

10: Did you go to college to become a meteorologist and what kind of training does it take?

You can get certified with a four-year degree, a bachelor's degree in an atmospheric science program. Some of the programs can also be within geography. That schooling consists of mathematics and a lot of science. So if you like science and math and are also interested in the weather, this might be the field for you. The American Meteorological Society is an organization that can also provide certification for certain career fields. (From Levi in Mrs. Rice's class at Mill Creek Elementary in Middleton)


May 2007

Thanks to Scott Dorval and Robyn Heffernan, meteorologists for their answers.

1: Can animals predict the weather?

I'm not sure they predict the weather, but they can certainly sense it. There's sometimes a feeling in the air when the pressure changes that animals can sense. We can sense that too, but maybe we're not as attuned as animals might be. I have heard many reports that before tornadoes hit; it gets very, very still. Birds stop chirping and the animals disappear. They know something is happening. That same eerie calm apparently happens before hurricanes, as well. (From Mr. Brassy's class at White Pine Elementary in Boise)

2: What are dust devils and how much damage can they cause?

A dust devil is thin, like a tornado, but it is certainly much, much weaker. It is caused by a very hot surface and low pressure in the center of that. The winds that whirl around that hot center point usually kick up dust around it. Dust devils are weak, but they have been known to cause a little bit of damage. Certainly not even what the lowest scale tornado would do, but a little damage - banging up signs or whatnot. (From Trevor at Maple Grove Elementary in Boise)

3: Has anyone ever survived being hit by a lightening bolt?

Actually that happens often. Lightning bolts hit people and some do survive. Unfortunately, many people who are struck by lightning and survive have a lot of medical problems after that. It actually can affect the body's nervous system. It's better not to tempt fate.

We always try to let everybody know that lightning safety is so important. If you are caught in a storm, try to get indoors. That's the safest place. If you are out-of-doors, try to get inside a car and not touch any metal part of the car. If you have no other choice, the best thing to do is to crouch down to the ground like you're in a ball and just have your toes touching the surface. You want to have the least amount of your body touching the ground.

Electricity is likely going to hit something tall, and you don't want that to be you. If it hits a nearby tree, the lightning could travel down the tree and along the ground. That's why you're on your toes, so there is less contact between you and the ground. (From Mitchell in Mrs. Woodall's class)

4: What was the deadliest hurricane?

By deadliest, I assume you mean the loss of human life. The deadliest hurricane of that type happened in the early 1900s. It was called the Galveston Island hurricane. Back then, they did not have the protections that we do today against those types of storms. At that time, there were reports of the hurricane from Cuba, but Galveston Island residents ignored those warnings. Galveston Island basically went underwater. Most of the individuals who lived there were killed - somewhere between 8,000 and 12,000 people. That's the deadliest. In terms of property damage, the worst hurricane was Katrina. (From Nadia in Ms. Childer's class at Hayden Meadows Elementary)

5: Can you get snow at the equator?

You can get snow anywhere it's cold enough. If a cold system dips that far south you can get snow, but typically, it does not occur because it's very warm there. But parts of Hawaii can get snow. You'll find it on the mountains on the Big Island and maybe other spots. You have to get high enough. People in Hawaii will hike up and ski down and then go surfing. Sounds like fun to me! (From Jessica in Boise)

6: Where is the worst weather in the world?

It all depends on what you mean by the worst weather. If you live in South Florida, you might think that temperatures dipping into the 20s are really bad. There are some basic kinds of severe weather: hurricanes, tornadoes, heavy rains and snowstorms, and major cold and heat waves. There are a lot of places that can have very difficult weather more often than other places. Nova Scotia, Canada, can get bad winter storms. There can be major storms in the Gulf of Alaska or in areas northwest of Idaho. And if you live in deserts in the Southwest, you can have temperatures topping 120 degrees. Those kind of conditions can be pretty bad. (From Eliseo in Ms. Lee's class at Gooding Elementary)

7: What should we do if we are in a tornado?

Tornado safety is very important. If a tornado is heading in your direction, you want to get in a solid structure - get out of mobile homes. If you live in a mobile home, talk to your parents tonight and ask where you would go. There's usually a solid structure nearby to evacuate to. Inside, you want to go to the lowest floor in an interior room and stay away from windows. Don't open the windows! The instruction to open windows is an old myth. (From Taylor in Ms. Lee's class at Gooding Elementary)

8: Could two tornadoes happen at once?

Absolutely. I saw a picture of a line of six tornadoes at one time. Sometimes when you have a thunderstorm swirling, it can produce multiple tornadoes. They are spinning and they are actually rotating around a center point, so you have individual tornadoes spinning around one central area. That usually means you're having a bad day when you see that. (From Joanne in Middleton)

9: Tell us about tornadoes. Why do tornadoes go through open land? Do they form in Idaho?

Tornadoes need wide, open spaces for forces to collide. That's what creates a tornado. Much of the central plains of America's Midwest, sometimes called Tornado Alley, are wide, open fields. It is rare for tornadoes to go over a major city, but when they do, that's when we get the most damage. When you look at a scale of zero to 5, the strongest tornadoes (level 5) only make up one or two percent of all tornadoes. We seem to get more tornadoes in eastern Idaho than in the rest of our state. Certainly we don't get the numbers they see on in the Midwest, but we get our fair share. Tornadoes in Idaho are typically rather weak, but in 2006 we had one of the strongest tornadoes I have ever seen right on the Oregon-Idaho border. We had winds of at least 150 miles an hour in that storm, and it ripped out all the trees in the town. It can happen. It's just a little rare. (From Alexis in Meridian; Thomas in Mrs. Hunt's class in Boise; and Mary in Mrs. Peterson's class in Meridian)

10: How do weather forecasters know how to predict the weather?

We need to gather lots of information. We have satellites to bring us information on clouds. We have weather stations that give us current weather data from around the globe at one particular point in time, and we have computer forecast models. We can look and see how weather patterns will change over time. Meteorologists also study lots of weather maps. Computer models help us with short-range forecasting - what the weather will be tomorrow - and we have extended-range forecasting to help us figure out the weather for next month and the following season. (From Lindsey in Mrs. McCamish-Cameron's class at Cynthia Mann Elementary in Boise)


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