Predicting the Weather
- Grades: 3–5, 6–8
The following questions were answered by meteorologists Barbara McNaught Watson and Al Peterlin.
Q: How do you find information about weather?
A: Meteorologists in the United States get most of their information from the National Weather Service, the federal agency that makes weather observations, runs weather computer models, and provides the information to TV and radio stations for release to the public. Weather people watch specific observations from many, many cities for signs of rain or violent weather approaching. We watch temperature, dew point, winds, and upper level winds for clues. We also use computer models to help guide us, but experience is still one of the best teachers. (Al Peterlin)
Q: How do you find out the weather every day?
A: We learn about the weather by collecting data (weather observations of temperature, wind, and humidity) every hour of the day and night all over the world. We then plot the data on maps, study the patterns for trends (the way things seem to move) and run computer models. Weather generally moves west to east in the United States, so you can sometimes look to the west for an estimate of your weather in a few hours or the next day. (Al Peterlin)
Q: How is weather formed? Also, how can you predict the weather one or two days in advance?
A: Almost all weather conditions begin because of the sun. The sun provides the energy to raise temperatures, and the uneven warming (water warms slower than soil and soil in the shadows warms slower than soil in the sun) triggers movement of air. Add in the spinning of the earth, and you have a very primitive weather-producing machine.
We make our forecasts, one and two days before, by observing weather conditions at the moment, putting it into a computer model, and then fine-tuning the results. Practice is very important, but we all still miss some forecasts. An easy way for you to practice making a forecast for, say, Georgia, is to look at the weather report for Alabama and Mississippi and to predict that weather for Georgia the next day. Watching the clouds pass by is also a good way to learn about weather. (Al Peterlin)
Q: Is there any way to predict how severe a winter will be?
A: The winter of 1995 was a record type of year and it is unlikely that we would have two years in a row like that. However, we have no good means of forecasting what the winter will be like. Meteorologists use computer models to help them forecast the weather. Our best forecasts are for about two days ahead. We have some accuracy forecasting as far ahead as seven days. The Climate Analysis Branch of the National Weather Service in Washington, D.C., tries to forecast whether parts of the country will be above or below normal for temperatures and precipitation. They look at global weather patterns and trends. They also watch for things such as the warming of the equatorial waters in the Pacific Ocean, which can cause the jet stream to shift and change the weather of the United States. However, beyond a month, the skill is not there. You could flip a coin and have as good a chance in being right. We still have so much to learn. Some people try to relate the upcoming winter weather to the type of summer we had and what has happened historically. This would say it will be a mild winter. The Climate Analysis Branch says that there is a slightly greater than 50 percent chance that temperatures will average above normal, but this says nothing about snow. The Farmer's Almanac says it will be a harsh winter. Some people say we have returned to the weather patterns of the 1960s during which there were many big snowstorms. In other words, we don't really know but it gives people something to talk about. It gives the meteorologists something to strive for, to continue to learn more about the weather patterns and someday predict what the upcoming winter will be like. (Barbara McNaught Watson)
Q: What makes one day beautiful and another stormy?
A: In our atmosphere (sky) there are many small differences in sunny and cloudy days. Temperature can be different, humidity is very different, wind direction changes, and there is usually something to trigger a change, like a weather front cold or warm along with the clouds. It can sometimes be to difficult to see the small changes, but a careful, very detailed observation will usually spot the differences. (Al Peterlin)
Q: Does it surprise you sometimes when it's suppose to be sunny, but it rains or snows that day?
A: Weather is what happens to us every day a day at a time. We try to forecast weather sunny or cloudy, wet or dry, and the temperature for one day, a second day, and then for a three to five day outlook. Do you know the difference between a forecast and an outlook? (Al Peterlin)
Q: Do you think we will be ever be able to control the weather, for instance, make it sunny on a cloudy day?
A: I doubt we will ever be able to fully control the weather. To do so we would have to understand the sky, the oceans, and all the effects of geography, like the height of mountains and many other events. There is a term scientists use, called "chaos," and weather is one of the natural events that involves a chaotic variable. This means a very small event, like a drop of water on a perfectly still pond will spread a ripple a great distance away. Then drop a second drop of water, and a third will have similar but slightly different effects and you can see how hard it gets to follow the waves. I keep a picture of a warm, sunny day in my mind for use on cloudy days. (Al Peterlin)