Since the dawn of time, weather has had an impact on humans and how they live, what they do and when. Today, there is an unbelievable array of land-based and satellite-based equipment to help monitor, track and predict the weather, but one primitive tool still used widely is the weather vane.

Weather vanes are common fixtures on the tops of buildings large and small. The earliest known weather vane was constructed atop Athens' Tower of the Winds by an astronomer in 48 B.C., but you've probably seen them topping everything from a historical government building to your neighbour's barn. For official purposes, wind is usually measured at a height of 10 metres or 33 feet, making such edifices the perfect location to install a weather vane.

Now often relegated to uses no more pressing than decoration or folk art, weather vanes were once key indicators of wind direction, which affected decisions from farming to flying. Sophisticated, modern weather vanes use wind data loggers (or computers) to create a history of wind direction. Direction, which is reported in terms of which direction the wind is coming from, not going to, is a key indicator for surface weather analysis and prediction, and therefore, very useful information.

Sometimes called 'wind vanes', traditional weather vanes are generally comprised of several parts, including a rod, a large lower globe, directionals, and a smaller upper globe, all of which are fixed, and a rotating ornament on top. To accurately indicate wind direction, the ornament must have unequal area and unequal mass on either side of centre. This oddity allows for lovely freeform ornaments, or more traditional arrows, scrolls, banners, or silhouetted roosters, airplanes and other common shapes. Another popular ornament style is the swell-bodied kind: three-dimensional forms a few inches thick, often made of hammered sheet copper. Similarly, full-bodied ornaments are also three-dimensional, but are more realistic in their proportions that swell-bodied ornaments. Rooster ornaments are particularly popular atop church steeples thanks to a reported ninth century papal decree calling for a cock to be installed on every European church steeple or dome as a reminder of a prophecy made my Jesus and recorded in Luke 22:34, that the morning cock would not crow the morning after the Last Supper until Peter had denounced Him three times.

Medieval towers in Europe often flew fabric pennants so that archers would be able to see wind direction. The cloth pennants were later replaced by metal flags, the precursor of today's modern weather vanes.