Sunday 11 February 2018

Facts 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.

In the ninth century, rooster weather vanes were found on the top many church steeples. The Smithsonian magazine states that Pope Nicholas 1 had decreed that every church needed one to remind believers of a biblical prophecy of Christ about Peter, the disciple who would betray him after his crucifixion. Today, the rooster shape remains popular, not only for its shape that is well suited to catching wind but due to the symbolism attached to it of welcoming the day and the light after the darkness.

The pointer on the weather vane has to be the right shape and it has to move freely. The pointer is larger at one end and tapered at the other. The large end catches wind and turns to point where it is going while the small end swings to point 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.

Beneath the point on a wind vane, it usually has fixed markers. There are four markers for each direction of the compass. If the arrow points toward the marker for south on the vane, it shows that wind is blowing from the south. If it is pointing to the west, wind is blowing from the west and towards the east.

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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