A Timeless History
Among the oldest weather instruments there are. Around 100–50 BC, Andronicus of Cyrrhus built the Tower of the Winds in Athens: an octagonal marble tower with a wind god carved on each side and a bronze Triton on the roof that turned to point at the blowing wind. For centuries after, farmers, sailors and travellers read the weather from a vane, long before forecasts existed.
SourceEncyclopaedia Britannica, Tower of the Winds · Vitruvius, De architectura I.6 · Image: Stuart & Revett, The Antiquities of Athens — Wikimedia Commons (PD)
Science In Action
Torque — a push acting away from the pivot makes it turn; the further out, the stronger the effect • Balance — the vane is balanced on its pivot, so gravity cannot turn it; only the wind can • Surface area — the broad tail catches more wind than the narrow head, so the tail swings downwind • Sensitivity — a well-balanced vane turns in a breeze too faint to feel on your skin
SourceNOAA National Weather Service, glossary: wind direction · Encyclopaedia Britannica, weather vane · Image: NOAA Photo Library, wea01316 (PD)
Arts
Vanes became sculpture. Roosters, horses, ships, dragons, arrows: from the weathercock on the church steeple to the moulded copper vanes of 19th-century American farms, finished in gold leaf so they caught the sun as well as the wind. The Smithsonian's gilded Prancing Horse is one of them.
SourceSmithsonian American Art Museum, folk art collection · Image: Prancing Horse Weathervane, 19th c., SAAM 1992.12.2 (CC0)
Applications Today
Aviation — every runway has a windsock; pilots read it before take-off and landing • Wind farms — a small vane on each turbine tells the yaw motors to turn the rotor into the wind • Weather stations — wind direction is still one of the first readings taken, every hour
SourceFAA, Advisory Circular 150/5345-27F · U.S. Department of Energy, How a wind turbine works · NOAA National Weather Service · Image: airport windsock, Frankenmuth, Michigan — Wikimedia Commons (CC0)
The Tower of the Winds still stands in Athens: twelve metres of marble, a wind carved on each of its eight sides.