Wind
direction
From Wikipedia, the free encyclopedia
Wind direction is reported by the direction from which it originates. For example, a northerly wind blows from the north to the south.[1]
Wind direction is usually reported in cardinal directions or in azimuth degrees. For example, a wind coming from the south is given
as 180 degrees; one from the east is 90 degrees.
Measurement
methods
There are a variety of instruments
used to measure wind direction, such as the windsock
and wind vane. Both of these instruments work by moving to minimize air
resistance. The way a weather vane is pointed by prevailing winds indicates the
direction from which the wind is blowing. The larger opening of a windsock
faces the direction that the wind is blowing from; its tail, with the smaller
opening, points in the direction the wind is blowing.
Modern instruments used to measure
wind speed and direction are called anemometers
and wind vanes
respectively. These types of instruments are used by the wind energy industry,
both for wind
resource assessment and turbine
control.
In primitive situations where these
modern instruments are not available, a person can use the index finger to test
the direction of wind. This would be done by wetting the finger and pointing it
upwards. Thus, the side of the finger which feels cool is the direction from
which wind is blowing. The coolness is caused by an increased rate of
evaporation of the moisture on the finger due to the air flow across the
finger, and thus the "finger technique" of measuring wind direction
does not work well in either very humid or very hot conditions. The same
principle is used to measure the dew point
(using a sling psychrometer, a more accurate instrument than the human finger). One may
also take a pinch of grass and drop it, the direction that the grass falls is
the direction the wind is blowing. This last technique is often used by golfers
because it allows them to gauge the strength of the wind as well.
The wiki link on this subject can be found at: http://en.wikipedia.org/wiki/Wind_direction
Do you know the cardinal directions from where you live,
like north, south, east, and west? Even directions which are often in-between,
can be called northeast, or even north northeast for another direction.
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