MadSci Network: Earth Sciences |
A meteorologist needs to know only two things to make a forecast...what the weather is at the moment and how the atmosphere behaves. Sounds simple, right? Knowing the state of the atmosphere at a given time involves taking simultaneous observations at many points on the surface of the earth, as well as in the layers of air above the surface. Surface observations are taken every hour at airports and other sites across the United States and every six hours around the world, including ships at sea and tethered buoys in the ocean. These amount to over 3000 observations every hour. Twice a day, at 0000Z and 1200Z (read about Zulu time at USATODAY), upper air observations are made using balloons, pilot reports, special upward-looking radars called profilers, and satellite sounders. Knowing how the atmophere behaves involves the study of atmospheric physics. The atmosphere conforms to the physical laws of nature and over the years, atmospheric scientists have described this behavior using numerical equations. Meteorologists study these laws and equations to understand why the atmosphere behaves the way it does, and to build computer models of the atmosphere. Forecasts can be made by a variety of methods. Some methods move the weather from one region to another with little change in the weather pattern as it moves. Some methods use computer models to change the weather patterns in time as well as space. You can read about these and others at this page from a class at Texas A&M University. Forecasters take all of what they know about the state of the atmosphere at a point in time (the observations) and feed this information into computer models. These models then step forward in time, changing the modeled atmosphere according to the way the equations say the real atmosphere should change. The forecaster then takes what the model says, evaluates it, modifies it where he or she thinks necessary, and translates it into pictures and words you see and hear on the internet, radio, and TV. You can learn more about computer models and weather forecasting at the National Weather Service's Hydrometeorological Prediction Center, and USATODAY's weather pages.
Try the links in the MadSci Library for more information on Earth Sciences.