Meteorologist

The term meteorology goes back to the book Meteorologica (about 340 BC) by Aristotle, who combined observations with speculation as to the origin of celestial phenomena. The Greek word meteoron refers to things "high in the sky", that is between Earth and the realm of the stars, while logos means "study". A similar work, called "Book of Signs", was published by Theophrastus, a pupil of Aristotle. It was centered more on predicting the weather by interpreting established celestial phenomena, such as a halo around the moon, without asking for explanations.

Further progress in the meteorological field had to wait until accurate instruments were available. Galileo constructed a thermometer in the 1500s, followed by Torricelli's invention of the barometer in 1643. The dependence of atmospheric pressure on height was first shown by Blaise Pascal and René Descartes. The anemometer for measuring wind speed was constructed in 1667 by Robert Hooke, while Horace de Saussure completed this list of the most important meteorological instruments in 1780 with the hair hygrometer, which measures humidity.

Other advances that are usually thought of as part of the progression of physics were Robert Boyle's investigation of the dependence of gas volume on pressure which lead to thermodynamics and Benjamin Franklin's kite experiments with lightning.

The first essentially correct explanation of global circulation was the 1735 study by George Hadley about the trade winds, which gave rise to calling the tropical cell of zonal mean atmospheric circulation "Hadley cell". In 1835, Gaspard de Coriolis recognized that the rotation of Earth causes a velocity-dependent force on bodies in the reference frame of a nonrotating Earth.

Synoptic weather observations were still hindered by the difficulty of establishing certain weather characteristics such as clouds or wind. These were solved when Luke Howard and Francis Beaufort introduced their systems for classifying clouds (1803) and wind speeds (1806), respectively. The real turning point however was the invention of the telegraph in 1843 that allowed exchange of weather information with unprecedented speed.

Early in the 20th century, theoretical studies of atmospheric phenomena usually were performed analytically, that is by taking the fluid-dynamical equations that govern atmosperic flow, simplifying them by neglecting lesser terms, and looking for solutions to these equations. For example, Vilhelm Bjerknes developed the model that explains the generation, intensification and ultimate decay (the lifecycle) of midlatitude cyclones, introducing the idea of fronts, that is, sharply defined boundaries between air masses.

Starting in the 1950s, numerical experiments with computers became feasible. The first weather forecasts derived this way used barotropic (that means, single-vertical-level) models, and could successfully predict the large-scale movement of midlatitude Rossby waves, that is, the pattern of atmosperic lows and highs.

In the 1960s, the chaotic nature of the atmosphere was first understood by Edward Lorenz, founding the field of chaos theory. The mathematical advances achieved here later filtered back to meteorology and made it possible to describe the limits of predictability inherent in atmospheric modelling. This is known as the butterfly effect, because the growth of disturbances over time means that even one as minute as the flapping of a butterfly's wings could much later cause a large disturbance to form somewhere else.

In 1960, the launch of Tiros 1, the first weather satellite marked the beginning of the age where weather information is availabe globally. Weather satellites along with more general-purpose Earth-observing satellites circling the earth at various altitudes have become an indispensable tool for studying a wide range of phenomena from forest fires to El Niño.

In recent years, climate models have been developed that feature a resolution comparable to older weather prediction models. These climate models are used to investigate long-term climate shifts, such as what effects might be caused by human emission of greenhouse gases.

Meteorological instrumentation that is used at the surface or in airplanes also has room for improvement. radar and lidar show precipitation and clouds by their effects on emitted monospectral electromagnetic waves. If radar measurements can be used to accurately determine the amount of precipitation (which as of now is only possible with rain gauges), this would be beneficial for numerical weather prediction. Lidar can be used to study clouds that are so thin that they cannot be seen by the naked eye such as certain types of cirrus filaments. Researchers continue to find new atmospheric details such as high-altitude clouds that can form from contrails, which suggest that air travel may affect regional weather.

• precipitation, atmospheric pressure, dew point, weather front, jet stream, windchill, heat index, Theta-e, primitive equations

• hurricane or typhoon

• Thunderstorm, lightning, thunder, hail, tornado, convection, hailstorm, blizzard

• El Niño, monsoon, flood, drought

• dust devil, fog, tide, wind, clouds, cloud, air mass, evaporation, sublimation, ice

• See weather disasters, weather related fatalities, extreme weather

Meteorological Instrumentation and Equipment

• anemometer, barometer, hygrometer, thermometer, radar, satellite, Doppler radar, rain gauge, weather vane, disdrometer, weather balloon

Institutions of Meteorology/Atmospheric Science