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الأحد، 8 أبريل 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 first weather vane was built in Ancient Greece by Andronicus, A Greek astronomer. It was built out of bronze in honor of Triton, a Greek god. A wand in his hand indicated wind direction from the top of a tower in Athens. Its head and torso were that of a man and it had the tail of a fish.

With the conversion of the Roman Empire to Christianity, a rooster began to appear on church steeples. It reminded believers of the need to be watchful because Jesus prophesied that Peter would deny him before the cock crowed three times. The tail of a rooster is just the right shape to catch the wind and its force is greater on the tail than the head. It gets pushed away so the head turns into the wind. This is probably why the rooster design remains so popular to this day. It also has symbolic relevance in that it welcomes the dawn and the triumph of light over darkness.

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.

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.

Knowing about where the wind was coming from was a great help to farmers in the past. They would examine the signs daily and put together their knowledge about the local area and climate to make their predictions. This could help them plant their crops in the right places and protect them. Today, we no longer need to determine weather by using weather vanes. We have plenty of modern instruments that are far superior. However, the appeal of this instrument remains and many people still enjoy placing them on their homes.




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