Sunday 11 February 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.

The weather vane is shaped aerodynamically. The one end of its pointer is thicker than the other and has a larger surface area. This enables it to catch wind and turn the pointer. The large end points to where wind is going and the small end to where it is coming from.

A weather vane that is shaped correctly and has balance will spin freely. If it is not precisely balanced, it will shift or topple and even stop moving. The weight needs to be equally distributed on either side of the axis or the vane will not spin freely. Some modern weather vanes do not have the necessary weight balance. They are designed more as architectural ornaments than for determining wind direction.

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.

By looking at wind patterns and changing directions, observers may be able to make simple predictions about the weather. Knowing that the west is wet and the east is dry, they know what to expect when a wind comes from either of those areas.

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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