Saturday, October 25, 2008

How much people depend on weather reports

Meteorologists on television, radio, online, and in newspapers supply weather reports to the average person over 100 times a month. Surveys demonstrated that the 300 billion forecasts accessed generate a value of $285 per household every year, or $32 billion for the entire United States. Odds are you have already watched one weather forecast today and will probably check out a few more. Accurate, timely forecasts are vital to everyday life, but just how critical may surprise you. Whether at work or play, you probably watch the weather quite closely. Most of us are at the weather person's mercy to know what to wear, what to expect, to prepare for the worst. New research shows the average United States household checks out a weather report more than three times a day.


"It impacts pretty much every part of every activity we are involved with for the most part," Jeff Lazo, the director of the Societal Impacts Program at the National Center for Atmospheric Research (NCAR) in Boulder, Colo., told Ivanhoe. To find out how important weather information is to people, meteorologists and economists at NCAR surveyed 1,500 people across the country. "Some people say I don't really actually get it that much, but when you think, you get it from the newspaper in the morning, hear it on the radio driving to and from work, see it on TV a couple of times in the evening," Lazo says. The findings ý most people watch the weather on local TV or cable than listen on radio or look online and in newspapers -- 115 times per month. "When you multiply that then times the whole U.S. population and times twelve months a year, we estimate about three-hundred-billion forecasts a year."

Weather reporting ý a whopping $30 billion-a-year business. Fortunately, per person that's less than a dollar a day, but invaluable for most of us. The survey information will be used to support funding the national weather service for congress.

WHAT'S THE FORECAST: Weather forecasting is the application of science and technology to predict the state of the atmosphere for a future time and a given location. Humankind has attempted to predict the weather since ancient times. For millennia people have tried to forecast the weather. In 650 BC, the Babylonians predicted the weather from cloud patterns. In about 340 BC, Aristotle described weather patterns in Meteorologica. Chinese weather prediction lore extends at least as far back as 300 BC. Ancient weather forecasting methods usually relied observed patterns of events.

For example, it might be observed that if the sunset was particularly red, the following day often brought fair weather. This experience accumulated over the generations to produce weather lore. Today, weather forecasts are made by collecting data about the current state of the atmosphere and using computer models of the atmospheric processes to project how the atmosphere will evolve.

HOW DO METEOROLOGISTS PREDICT THE WEATHER? Weather forecasting is an inexact science, and many different methods are used in combination to make a prediction. The "climatology method" averages weather statistics gathered over many years for a specific region to make a prediction. But this only works when the weather pattern is similar to what is expected for the chosen time of year. Taking it to the next level, meteorologists examine a forecast and then look to a day in the past where the conditions were very similar -- and then predict that the current weather is expected to behave like that.

However, tiny differences in conditions can make big differences in the actual weather. Radar systems send a signal -- usually microwaves -- towards an object or region, and then analyze how long it takes for the signal to be reflected back. Those results can reveal valuable information about the weather.

WHAT IS DOPPLER RADAR? Doppler radar uses a well-known effect of light called the Doppler shift. Just as a train whistle will sound higher as it approaches a platform and then become lower in pitch as it moves away, light emitted by a moving object is perceived to increase in frequency (a blue shift) if it is moving toward the observer; if the object is moving away from us, it will be shifted toward the red end of the spectrum. Doppler radar sends out radio waves that bounce off objects in the air, such as raindrops or snow crystals, and then measures how much the frequency changes in returning radio waves to better determine wind direction and speed.
Credits: American Meteorological Society.

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