Saturday, April 25, 2015

Notes on weather...

Early History
The art of weather forecasting began with early civilizations using reoccurring astronomical and meteorological events to help them monitor seasonal changes in the weather. Around 650 B.C., the Babylonians tried to predict short-term weather changes based on the appearance of clouds and optical phenomena such as haloes. By 300 B.C., Chinese astronomers had developed a calendar that divided the year into 24 festivals, each festival associated with a different type of weather.
Around 340 B.C., the Greek philosopher Aristotle wroteMeteorologica, a philosophical treatise that included theories about the formation of rain, clouds, hail, wind, thunder, lightning, and hurricanes. In addition, topics such as astronomy, geography, and chemistry were also addressed. Aristotle made some remarkably acute observations concerning the weather, along with some significant errors, and his four-volume text was considered by many to be the authority on weather theory for almost 2000 years. Although many of Aristotle’s claims were erroneous, it was not until about the 17th century that many of his ideas were overthrown.
Throughout the centuries, attempts have been made to produce forecasts based on weather lore and personal observations. However, by the end of the Renaissance, it had become increasingly evident that the speculations of the natural philosophers were inadequate and that greater knowledge was necessary to further our understanding of the atmosphere. In order to do this, instruments were needed to measure the properties of the atmosphere, such as moisture, temperature, and pressure. The first known design in western civilization for a hygrometer, an instrument to measure the humidity of air, was described by Nicholas Cusa (c.1401-1464, German) in the mid-fifteenth century. Galileo Galilei (1564-1642, Italian) invented an early thermometer in 1592 or shortly thereafter; and Evangelista Torricelli (1608-1647, Italian) invented the barometer for measuring atmospheric pressure in 1643.

Forecasting from the Beginning
Our brief exploration into forecasting pretty much follows the techniques and methods developed by early weather wizards. From the earliest of times, hunters, farmers, warriors, shepherds, and sailors learned the importance of being able to tell what the weather might be up to next. Ancient civilizations appealed to the gods of the sky. The Egyptians looked to Ra, the sun god. The Greeks sought out the all-powerful Zeus. Then there was Thor, the god of thunder and lightning in ancient Nordic times. Some societies, such as the Aztecs, used human sacrifice to satisfy the rain god, Tlaloc. Native American and Australian aborigines performed rain dances. Those who were able to predict the weather and seemed to influence its production were held in highest esteem. After all, they appeared to be very well connected.

One of the earliest scientific approaches to weather prediction occurred around 300 B.C.E., documented in Aristotle's work, "Meteorologica." The ancient Greeks invented the term meteorology, which means the study of atmospheric disturbances or meteors. Aristotle tried to explain the weather through the interaction of earth, fire, air, and water. His pupil Theophrastus really went to work and wrote the ultimate weather text The Book of Signs, which contained a collection of weather lore and forecast signs. Amazingly it served as the definitive weather book for 2,000 years! (What if they're still reading this 2,000 years from now?)
Theophrastus's weather lore included colors of the sky, rings and halos, and even sound. Hippocrates—also known as "the Father of Medicine"—was also very much involved with the weather. His work On Airs, Waters, and Places became a medical classic, linking good health with favorable weather conditions. The opening of his work begins with the advice that those who wish to investigate medicine must first begin with an understanding of seasons and weather.

Weather forecasting advanced little from these ancient times to the Renaissance. Then beginning in the fifteenth century, Leonardo da Vinci designed an instrument for measuring humidity called a hygrometer. Later Galileo Galilei invented the thermometer and his student Evangelista Torricelli came up with the barometer for measuring air pressure. With these tools, people could monitor the atmosphere. Then Sir Isaac Newton derived the physics and mathematics that accurately described the atmosphere. Newton's work on motion remains The Book of Signs of modern meteorology. To this day, his principles form the foundation of all computer analyses and predictions.

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