Friday, July 15, 2011

A Brief History of Weather Forecasting - from Gods to Gigabytes

An Incredible Journey
Humanity’s effort to understand, and eventually predict the behaviour of our weather, has been one of the more remarkable odysseys of history.

In many early civilisations, the state of the weather was believed to be a direct reflection of the mood of the Gods who could punish the misdeeds of society with storms, drought and flood. As a result elaborate systems of prayer and ritual were constructed in order to appease these Gods, sometimes involving human sacrifice.

Ra – the Sun God of ancient Egypt (Image from Wikipedia Commons – click to enlarge)

The first “weathermen” were usually high priests, witchdoctors or medicine men, whose duties involved not only “foretelling” the weather but also ensuring that the Gods were placated so as to guarantee favourable conditions into the future.

The belief in the divine nature of weather continued across the millennia with hailstorms in mediaeval Europe, for example, sometimes being followed by the burning of witches.

Great Minds of Antiquity
However even in ancient societies inquisitive minds were at work to try and identify “natural” causes that drove the weather. Such great intellects as Hippocrates, Aristotle and Pliny the Elder all produced treatises on the subject, offering many ideas that were later shown to be incorrect but nevertheless demonstrating a desire to look beyond the supernatural.

Aristotle's treatise on th subject - Meteorologica - meaning a study of phenomena high in the air, was to give the modern science of meteorology its name.

Aristotle – believed that the weather was the result of natural forces rather than the moods of the Gods. (Image from Wikipedia Commons – click to enlarge)

Weather Folklore
Another source of progress in the “natural” understanding of weather came, not surprisingly, from the two main groups most intimately affected by it – farmers and mariners. Both noted correlations between the weather and cloud patterns, the nature of the wind and even changes in plant and wildlife behaviour.

The mariners, in particular, forged ahead steadily, and by the mid 1700’s sailing boat captains had gathered a good working knowledge of the main wind regimes of our planet, giving them nautical names that persist today, such as the Roaring Forties, the Trade Winds and Doldrums.

A formation of alto-cumulus - a "mackerel" sky.

"Mare's tails and mackerel scales make tall ships take in their sails." (Image from Wikipedia Commons – click to enlarge)

Whilst much of the “weather folklore” did not provide a lasting contribution to meteorology, it nevertheless formed a bridge between the Divine nature of weather and the Scientific Era that was to follow.

The Scientific Era
During the latter half of the Middle Ages, several exciting developments were made that would help catapult meteorology into the world of science, where it at once took root and flourished.

Instruments for measuring the state of the atmosphere were invented in the 15th, 16th and 17th centuries and were followed in quick time over the next 100 years by important discoveries on the chemical composition and temperature structure of the atmosphere.

During this time the hygrometer was invented by Leonardo da Vinci (1452 – 1519), the thermometer by Galileo Galilei, (1564 – 1642), and the barometer by Evangelista Torricelli (1608 – 1647).

Knowledge exploded during the 19th century with the discovery that large belts of high and low atmospheric pressure constantly circulated the globe, and the invention of the electric telegraph allowed this information to be transmitted faster than the pressure systems themselves, could move.

Samuel Morse (1791 – 1872) American inventor of the electric telegraph and the Morse code (Image from Wikipedia Commons – click to enlarge)

International cooperation in exchanging weather data was achieved in 1878 with the founding of the International Meteorological Organisation (IMO).

The 20th century saw progress accelerate at an astounding rate, with national meteorological services forming around the world and the beginnings of “weather forecasting by mathematics” off to a solid start, following pioneering work by the English scientist Lewis Fry Richardson.

The IMO evolved into the WMO - the World Meteorological Organisation in 1950, and soon attracted more than 170 member counties, all with the aim of generating and sharing weather information on a basis of global cooperation.

The first meteorological satellite was launched in 1960, and was accompanied by a steady increase in weather observing stations and radar installations right around the world.

The first photograph transmitted by TIROS 1 from space - 1960 (Image from Wikipedia Commons – click to enlarge)

Into The Future
By the beginning of the 21st Century meteorology had evolved into a vast, complex interdisciplinary science, with weather forecasts being produced out to seven days ahead by massive supercomputers linked to a vast international array of automatic weather stations, meteorological satellites and floating oceanic buoys.

Meteorology has become a glowing example of international cooperation with a developing science made available to all for the common good, sometimes within hostile political environments. If meteorologists ruled the world life could be rather dull but it would be peaceful.

New weather God - an SGI Altix supercomputer located in France is housed in a structure strangely reminiscent of a church (Image from Wikipedia Commons – click to enlarge)

The accuracy of weather forecasts has been steadily increasing, and with more computing power becoming available, together with an increasing density of meteorological observations, this increase is expected to continue well into the future.

The long march from Gods to gigabytes has been one of the epic journeys of humanity and provides a fascinating insight both into the weather and the almost infinite inventiveness of the human mind.

For m0re information on how computers are used to predict the weather see

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