- A weather vane is an ornamental, meteorological device. This practical instrument, which is almost always longer than it is wide, will, when correctly made and installed, point in the direction that the wind is coming from. Furthermore, when the wind changes or fluctuates its direction, the flat object will rotate immediately so that it is always pointing into the face of the wind. To be effective, a weather vane must be placed in a high place, where it can be seen from a distance.
- Weather vanes can be traced at least as far back as Greece in the years before the birth of Christ. They were also a part of the development of Christian Europe, where they appeared in such diverse places as churches, town halls, farmhouses, and they have even been found on Viking ships. Weather vanes were popular in Colonial America too, but the unusual contraption really seemed to have come into its own after the Revolutionary War. Even today, the weather vane still has some practical importance in that these popular rooftop ornaments always show a change in wind direction, which is often the harbinger of a change in weather.
- The weather vane is built in primarily a horizontal plane, but of the utmost importance is the vertical pole that is part of the ornament. The ornament is the highly visible object that sits on the top and is the largest part of the weather vane. Below this top piece, there is a small globe that allows the top piece or ornament to spin freely, while the rest of the weather vane, which is almost always in the form of a long rod, remains stationary.
- The vane features a design or sculptured object, often an animal such as a rooster or cow, which spins freely. There is also a fixed vertical rod, which is attached to a roof or some sort of high point. On the stationary rod, it is always necessary to have the four cardinal directions, north, south, east and west, boldly displayed, so that the observer can determine which direction the wind is blowing from. And, of course, the rotational motion of the ornament would not be possible without a spinning globe or joint between the top and bottom portions of the weather vane.
- Two things have to happen for the weather vane to operate correctly. First of all, the forward and rear part of the ornament have to be of equal mass. This allows the weather vane to rotate freely. Next time you look at a weather vane, be sure to notice that the highly decorated top is always mounted on a narrow pole or rod. This is the center line or axis of the "vane." The other property of the ornament is that the rear section must be greater in area than the front section. This last characteristic is what causes the vane to point into the wind.
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