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The Three Ways We Understand Our Atmosphere

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Creative Commons.

Have you ever heard someone poke fun at your local TV weathercaster, claiming "they never get it right"? Actually, great progress has been made over the last several decades in weather prediction. Not only are you less likely to have your picnic or soccer game interrupted by an unexpected storm, but there are huge financial benefits from even small improvements in forecasting. Just 1°F of improvement in tomorrow's high temperature forecast can mean thousands of dollars in savings for a utility that needs to assess how much electricity to generate for heating or cooling the next day.

Better day-to-day forecasts are one of the most obvious benefits of weather and climate research. These forecasts are produced largely from the models and data managed by the National Weather Service, but also through the contributions of many private companies that customize weather data and predictions to serve specific needs, whether it's a NASCAR race in Pennsylvania or an orange harvest in Florida. Government and university scientists contribute a great deal to the process by conducting behind-the-scenes research that helps lead to better forecasts.

All of these partners work closely together, giving the United States the world's largest and most diverse set of professionals who specialize in the atmosphere. This full team--representing public, private, and academic sectors--is sometimes referred to as America's "weather and climate enterprise."

How do scientists come up with better ways to predict the weather? The process hinges on three techniques, each one critical to success.

Observations are the starting point for understanding how weather and climate work. People have always looked at the sky, of course, and they have long documented the effects of weather, especially on water supply. Egyptians have used "nilometers" to gauge the height of the Nile River for more than 2,800 years. However, quantitative weather observation didn't begin until the late 1600s, when modern-day weather instruments such as the thermometer (for temperature) and the barometer (for atmospheric pressure) were developed. Weather watching became a trendy hobby among movers and shakers during the 1700s; in fact, Thomas Jefferson kept a weather diary for 50 years.

Networks of weather observers were able to share their findings quickly once the teletype was invented in the mid-1800s. That helped led to the creation of country-wide centers around the world, such as the U.S. National Weather Service (which was known for 80 years as the U.S. Weather Bureau). In the early 20th century, scientists began to observe the atmosphere in three dimensions with the help of radiosondes--instrument packages that sailed to space aboard balloons and sent back weather data via radio. After World War II, radar and satellite became vital tools for remote sensing: instead of measuring what was happening at a single weather stations=, scientists could now send out electromagnetic signals that bounce back and tell us what's happening at many points, both near and far.

Theory is essential for understanding how weather and climate function. One of the principles of atmospheric science is that the air behaves like a fluid. Normally, you can't see the air around us (unless it's polluted or foggy), but it actually flows in currents and waves very much like those in a river or the ocean. This concept has led to enormous advances over the last 100 years. By using equations that describe fluid behavior, scientists can explain how the atmosphere behaves in certain situations.

Another landmark in weather and climate theory was the creation of polar front theory in the 1910s. A group of brilliant meteorologists assembled in Bergen, Norway, and over several years they developed the concepts of cold and warm fronts that we now take for granted. They also detailed the life cycle of a prototypical low-pressure center as it develops along a front and triggers a variety of weather. By envisioning the boundaries between air masses as "fronts"--a term inspired by the battle lines of World War I--these scientists paved the way for many kinds of research progress.

Computer models combine theory and observation to simulate the weather we're likely to experience tomorrow--and the climate we can expect later this century. Like a complex video game, an atmospheric model tracks the movement of the atmosphere over time, using the equations of motion developed by theorists and incorporating weather data collected all over the world.

Today's prediction models are vastly more sophisticated than those used even a few years ago. Thanks to improved software and more powerful computers, forecasters can now run "ensembles" that produce 10, 20, or more variations on how tomorrow's weather might look. Each ensemble forecast originates from a slightly different starting point, which takes into account the uncertainty in our observations. If the ensemble members agree on rain, it boosts our confidence; if half predict rain and the other half don't, then we have good reason to hedge our bets.

Scientists are working on ways to improve each leg of the three-legged stool--data, theory, and models--that supports progress in weather and climate research. Like tomorrow's weather, our view of the future of weather and climate research isn't set in stone, but the outlook is promising.