A weather vane is a device used for determining the direction the wind is blowing. Weather vanes have been used since ancient times and have graced the steeples of grand cathedrals and the roofs of the most rustic barns. They were probably the first instruments ever used to measure and predict the weather. They have been used to indicate that a storm is coming and the crop must be brought in from the field. They have warned of a coming cold snap.
Andronicus, an astronomer, built history’s first recorded weather vane for the Tower of the Winds in Athens. Bronze weather vanes have been found by archaeologists among ninth-century Viking ships’ remains. In the ninth century, the pope is said to have decreed that every church steeple show a cock, making the rooster a popular icon in weather vanes. Weather vanes were used in Britain, Normandy and Germany to show archers the direction of the wind.
The Bayeux Tapestry of 1065 shows a weathercock vane being placed on Westminster Abbey. The oldest weather vane in Britain is believed to be at Ottery St. Mary, Devon, and dates to about 1340. It has whistling tubes so that the cock decoration makes a crowing sound. George Washington had a weather vane crafted for Mount Vernon in 1787. It is a dove of peace, and that weather vane still stands on the cupola at the first president’s estate. Thomas Jefferson is said to have had an indoor indicator that showed which direction his weather vane was pointing so that he wouldn’t be required to step outside to see the device.
Most weather vanes consist of a rotating ornament that points the direction at the top of a rod. The weather vane usually includes a small globe at the top of the fixed portion of the rod and a larger globe at the bottom of the rod. A directional that indicates north, south, east or west is usually affixed to the rod between the two globes.
A weather vane points in the direction from which the wind is coming. This means, for example, that if the wind is coming from the west, the arrow will point to the west. This would mean that if you were to face west, you would feel wind on your face.
If your weather vane changes from west to east, this may be a signal that a mass of lower pressure is overhead and will bring storms. If the weather vane indicates a shift from the south or southwest, this may indicate that warmer air is on the way. If the vane is swinging erratically, this means the air is unstable and the current weather conditions are changing.
For an in-depth explanation of how a weather vane works, view the video below: