Saturday 31 March 2018

Find Out About Weathervanes And How They Work

By Melissa Davis


A weather vane will point in the direction from which the wind is blowing. It is placed in the highest, most unobstructed location on a structure. It only works properly if the wind flows freely and is not blocked by trees or other buildings. For those who did not have our modern instruments for measuring wind direction and speed, weathervanes had great significance.

The earliest weather vane in recorded history was built by the astronomer, Andronicus. It honored the Greek God Triton and was a combination of man and fish. In ancient Greece and Rome, weather vanes depicting the gods adorned the dwellings of wealthy landowners.

It was in the ninth century that it was decreed that all churches must have a rooster weather vane on their domes or steeples. Roosters were used for hundreds of years after that on churches in Britain and America and they are still popular today. Perhaps this is because of their significance as a symbol of light conquering darkness and bringing in the dawn, or it could be simply because the tail of a rooster catches wind well. The force on the tail is greater than on the head and so the head swings to face the wind.

On a wind vane, the free-swinging directional pointer or arrow is thicker at the one end and thinner at the other. The larger end with the greater surface area catches the breeze. The small end turns to point in the direction from which a wind is coming, and the larger end turns to point where it is going.

If the weather vane has the correct shape and balance, it is able to move freely. If not, it may not move at all or shift when it moves. Weight has to be equally distributed on either side of the axis to enable it to move freely. In designing modern weather vanes, more consideration may be given to aesthetic appeal than the ability to determine wind direction as this is no longer considered necessary.

Directional markers are fixed below the pointer. They indicate north, south, east and west. When the arrow points towards the west, the marker for west shows that wind is blowing from that direction and toward the east. If the marker shows north, wind is blowing from the north and toward the south.

When observers look at changing directions and wind patterns, they can make simple forecasts. Forecasts are based on other factors too, such as knowledge or experience of local climatic conditions. If they know that the north is cold and the south is warm, for example, they know what to expect when wind comes from that direction.

Determining wind direction and what this meant was a daily consideration for farmers. Their first-hand observations, experience and local knowledge helped them in this exercise. Today, we do not need weather vanes for this reason but they continue to retain their appeal. A wide variety are available today in many different designs. Those that are designed correctly, still work in exactly the same way as they have through the centuries whilst others are valued for their aesthetic appeal.




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