lundi 12 février 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 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.

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 wind vane must be precisely balanced in order to be able to turn freely. Otherwise, it can topple or not move at all. To spin freely, weight has to be distributed equally on both sides of its axis. Some modern weather vanes are made purely for ornamental reasons and do not have this type of balance. They do not show wind direction because they lack this balance.

On the weather vane, just underneath the pointer, are fixed directional markers. They point towards the north, south, east and west. If the arrow is pointing toward the marker for north on the weather vane, wind is blowing from the north to 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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