What Is a Weather Vane Used for?

Weather vanes are also called weathercocks or wind vanes and, although they cannot actually predict the weather, they do show which direction the wind is blowing. Oftentimes this information is enough to help people who need to know, such as farmers, whether a storm is imminent or fair weather will continue, since the direction that the wind comes from is a key ingredient in putting together a weather forecast.

Function

The typical weather vane is constructed so that there is equal weight on each side of a rotating axis. The surface area, however, will be larger on one side. Breezes force the side with the bigger surface area to blow away from the incoming wind. The arrow or other pointer on the weather vane will then be pointing into the wind, indicating the direction from which the wind is blowing.

Types

The most functional of all weather vanes is a simple arrow design that clearly shows the wind direction. A banner weather vane is designed with an intricate pointer on one side and a pierced metal surface on the other that can display a special date or a monogram. A silhouette weather vane makes use of a cut-out form attached to a rod mounted on a building to indicate wind direction. The swell-bodied weather vane uses shallow molds that can turn out forms such as horses or dogs, which are then mounted on a roof.

Directions

The majority of weather vanes come with markers underneath the pointer that indicate the four directions: north, south, east and west. This apparatus must be correctly aligned by the installer so as to point to the correct direction. The weather vane must be mounted somewhere where it will receive the full force of a wind without any trees, structures or other things blocking or deflecting the breeze.

Benefits

Before the advent of sophisticated weather forecasting methods complete with Doppler radar, the weather vane was one tool a farmer would use when trying to determine what sort of weather might be brewing. In the winter, for example, a farmer living in a state such as Connecticut would be wary of possible bad weather when a strong northeast breeze was blowing. Winds from the south normally would be associated with warming trends, but those from the east often meant rain. A fair west wind would allow a farmer to plan his day accordingly, trying to get as much work as possible done outside before the weather, and the wind direction, changed.

History

The earliest known weather vane was constructed for the Tower of the Winds in Athens, Greece. It featured a pronged triton, a weapon associated with the god of the sea, to indicate the direction the wind was coming from. This vane dates to about 50 years before the birth of Christ. Over the centuries, the triton was replaced on ancient weather vanes by the rooster. The majority of churches would have a weather vane featuring a rooster, which was closely associated with St. Peter as he denied knowing Jesus three times before a cock crowed. The rooster also represents alertness, which served the ancient civilizations well as they attempted to predict the weather.