Everything about Weather Vane totally explained
A
weather vane, also called a
wind vane, is a movable device attached to an elevated object such as a roof for showing the direction of the wind. Very often these are in the shape of
cockerels and are called
weather cocks. Arrows are also popular, but a multitude of designs have been used.
Operation
The weather vane must be balanced so that half its weight is on either side of its axis, but also designed so that the momenta about the axis of the areas exposed to the wind are
unequal. This unequal momentum causes the vane to rotate to minimize the force of the wind on its surface. The design of the vane causes the end with the smallest momentum to turn into the wind, pointing to the source of the wind. Because winds are named from their source direction, the pointer enables the viewer to name the wind easily. Most simple weather vanes have directional markers beneath the pointer, aligned with the geographic directions. The pointer must be able to move freely on its axis.
Weather cocks, especially those with fanciful shapes, don't always show the real direction of a very gentle wind. This is because the figures don't achieve the design balance required in a weather vane: an unequal surface area but balanced in weight.
To obtain an accurate reading, the weather vane must be located well above the ground and away from buildings, trees, and other objects which interfere with the true wind direction. Changing wind direction can be meaningful when coordinated with other apparent sky conditions, enabling the user to make simple short range forecasts.
History
Early weather vanes had very ornamental pointers, but modern wind vanes are usually simple arrows that dispense with the directionals because the instrument is connected to a remote reading station. Also modern wind vanes are mounted with an
anemometer, a device that measures wind speed. Co-locating both instruments allows them to use the same axis (a vertical rod).
Weather stations of variable quality may be purchased, and these include wind vanes along with several other instruments with dials that can be read comfortably inside a home or office. Combining a
propeller for wind speed and a tail for wind direction on the same axis is an
aerovane, for accurate, precise measurements from a single instrument.
Another wind direction device is the
windsock used at airports to show wind direction and strength. The wind fills the sock and makes it blow away from the prevailing wind. Strong winds make the sock point almost horizontally, while light airs allow the sock to hang limply. Because of its size, the windsock can often be seen from the air as well as the ground. Even the most technologically-advanced airports still use windsocks.
According to the
Guinness World Records, the world's largest weather vane is located in
Jerez,
Spain. A challenger for the title of world's largest weather vane is located in
Whitehorse, Yukon. The weather vane is a retired
Douglas DC-3 atop a swiveling support. Located beside
Whitehorse International Airport, the weather vane is used mainly by pilots to determine wind direction. The weather vane only requires a 5 km/hour wind to rotate.
In
1840 Grand National one of the competitors in the
Grand National Steeplechase was named
Weathercock. The horse was a totally unconsidered outsider who failed to complete the first of two circuits of the course.
Slang term
The term "weathervane" is also a slang word for a politician who has frequent changes of opinion. The
National Assembly of Quebec has banned use of this slang term as a slur after its use by members of the legislature.
The word 'vane' comes from the Anglo-Saxon word 'fane' meaning 'flag'.Originally the people used flags to show the direction of the wind.
Gallery
Image:Wind speed and direction instrument - NOAA.jpg|Aerovane
Image:Rooster Weather Vane.jpg|Weather cock
Image:Windrichtungsgeber.jpg|Weather vane
Image:Sailing-ship-weather-vane.JPG | Weather Ship
Further Information
Get more info on 'Weather Vane'.
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