The size of these cells - the resolution of the model - affects its forecasting accuracy. Weather models divide a region, say a single state or even the whole globe, into a set of boxes, or cells. This allows meteorologists to simulate what the atmosphere is currently doing and predict what will happen in the next few days or, for some models, hours. Ground radar, weather balloons, aircraft, satellites, ocean buoys and more can provide three-dimensional observations that a model can use. The more current and accurate information available to these models, the better the forecast will be. Meteorologists use a process called numerical weather prediction to create forecasts by inputting current conditions - which they call the “nowcast” - into computer models. Today’s weather forecasts aren’t made by people looking at weather maps and yesterday’s highs and lows - they’re made by machines. Luckily, we have newer, better ways to predict the future. Persistence is an OK way to predict the weather when conditions are constant - when a storm trundles along without breaking up or the local climate changes little day to day, say, in Southern California.īut this simple technique doesn’t account for changing conditions, such as storms that form quickly through convection (typical for thunderstorms) or moving fronts that change the temperature. “If a storm system is in Kansas one day and Missouri the next, then by persistence you can say it’ll be in Illinois the next day,” explains Bob Henson, a meteorologist who writes for Weather Underground. By the late 1800s, rudimentary weather maps had come into common use.īut early forecasts were limited and relied on persistence, or the assumption that a system’s past would dictate its future behavior. European scientists of old, like Galileo, used these instruments to take the types of measurements that would one day explain weather events. Scientific weather observations began in the Renaissance, when barometers and thermometers were invented. We cannot do that in economics or sports,” says Falko Judt, a research meteorologist at the National Center for Atmospheric Research in Boulder, Colorado.ĭoing so depends on reliable observations. “Weather forecasting is one of only a few fields where we can accurately forecast the evolution of a system. With so many factors involved, it may seem impossible to predict what weather is on the horizon. If it finds more warm air and moisture - like a hurricane does as it moves across the ocean - it will grow and grow. Once a storm has formed, if there’s nowhere for it to get more moisture from the ground or the air, it will peter out as it lumbers along. These droplets are carried aloft by rising air, growing larger and larger until they become too heavy and fall back to Earth. As warm, moist air rises, it also cools, and its water condenses onto airborne particles such as dust. It’s not just fronts that can make it rain convection can also drive precipitation. Sometimes these cloudy clashes can cause rain, as the cooling warm air is forced to drop its water. When regions of air with different temperatures and densities meet, the boundary is called a front. Weather is simply the byproduct of our atmosphere moving heat from one place to another.Ĭooler air is dense and can’t hold much moisture warmer air is less dense and can hold more water. As air flows from one place to another, it carries its properties with it, changing the temperature, humidity and more. This air, like liquid water, behaves as a fluid. To do that, we must look to the sky.Įarth is enveloped in an atmosphere of mostly nitrogen, oxygen and water vapor. Making the Weatherīefore we can predict the weather, we have to understand where it comes from. And meteorologists in pursuit of an ever-more-perfect forecast continue to push what’s possible toward its theoretical limit. In reality, weather forecasts have improved in leaps and bounds in just the past few decades. You’ve probably heard the joke: Meteorology is the only occupation where you can be wrong all the time and still get paid for it. “Storms and all the other interesting things that Earth’s atmosphere brings us have this big effect on our daily lives in a lot of ways.” But even though we tune in to local news stations or check apps to find out what the weather will bring, we don’t always trust the forecasts. “It’s what’s going on in the atmosphere all around us all the time,” says Russ Schumacher, Colorado State climatologist and director of the Colorado Climate Center. Few things in our lives are as universal as the weather. Those two simple words can ruin picnic plans or herald rescue for drought-stricken crops.
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