Meteorology, << `mee` tee uh ROL uh jee, >> is the study of the earth’s atmosphere and the variations in atmospheric conditions that produce weather. Meteorologists measure precipitation and such conditions as wind, temperature, and humidity. They also collect and measure gases, such as ozone and carbon dioxide, that occur in the atmosphere. Meteorologists use the data they gather to study and predict weather and climate. The word meteorology comes from Meteorologica, the title of a book by the ancient Greek philosopher Aristotle. In this book, Aristotle included his explanations of various weather conditions.
Meteorologists can predict the weather as far ahead as a few days. Their forecasts include ranges of temperature and cloudiness, and the chances of rain or snow. A forecast may also warn of strong winds, floods, hail, or severe air pollution. When dangerous weather conditions, such as hurricanes, tornadoes, or blizzards, are expected, meteorologists work with government officials and the public to develop emergency plans.
Some forecasters work for government agencies. Others work in television or radio and for airlines and power companies. Some meteorologists act as private consultants to groups especially dependent on weather, such as farmers and builders.
Many meteorologists conduct research. Some work to improve the use of computers in predicting the weather. Others develop observation instruments. Still others study the causes of such events as tornadoes and floods.
How meteorologists measure the atmosphere.
Meteorologists gather information about the atmosphere from land, at sea, in the air, and even from outer space. They use a variety of instruments, including thermometers; barometers, which measure air pressure; and hygrometers, which measure humidity.
Meteorologists track severe storms with Doppler radar, which can detect changes in wind speed or direction. They also rely on reports of storm spotters, people who watch for storms. Ocean buoys record air and sea conditions. Specially equipped aircraft and weather balloons provide data that meteorologists use to determine the temperature and humidity of the air and the speed and direction of winds. Meteorologists use weather satellites to follow storms and to estimate wind speeds. They also use data gathered by satellites to estimate temperature and humidity and to measure ozone.
Computer modeling.
Meteorologists make extensive use of computer models to predict the weather. A computer model, sometimes called a numerical weather prediction model, is a set of mathematical equations processed by computers. The equations simulate (represent) how weather systems form and change.
A simulation begins with the current state of the atmosphere, as determined by the most recent observations. First, the computer predicts the state of the atmosphere after a specific time interval—for example, the next 90 seconds. Using the new state as a starting point, the computer then makes a forecast for 90 seconds later. This process repeats until the computer has produced forecasts for the next 12, 24, 36, and 48 hours. Computer models also produce weather maps.
History.
Scientific observation of the weather began in 1593, when the Italian astronomer and physicist Galileo invented a thermometer to measure air temperature. By the late 1700’s, people had invented instruments to measure humidity, wind speed, air pressure, and precipitation. During the 1800’s, scientists used weather maps to forecast the weather.
In the early 1900’s, meteorologists began to explain the structure of the atmosphere. The Norwegian meteorologist Vilhelm Bjerknes discovered that the atmosphere contains zones of rapidly changing conditions called fronts. In the late 1940’s, the Swedish-American meteorologist Carl-Gustaf Rossby studied jet streams, which are atmospheric regions of extremely strong winds. Satellites became important in weather forecasting in the 1960’s.
By 2000, meteorologists throughout the world had taken advantage of much improved technology. For example, extensive networks of Doppler radars helped forecast severe storms in the United States. Meteorologists also used powerful computers to quickly analyze data and make forecasts.
