Introduction to Measuring Wind Direction
If you are wondering how to measure wind direction, you have a number of simple yet accurate options at your disposal. Wind direction, described according to the compass point where the wind originated, can be measured using any one of a variety of widely available instruments. While professional meteorologists employ sophisticated machines for highly accurate readings, anyone can measure wind direction using the following methods.
The Ornamental yet Functional Weather Vane
One of the most common ways to measure wind direction is through the use of a weather vane. Available in an assortment of designs, weather vanes work by spinning on a rod when the wind blows. Regardless the design, one end of the weather vane is larger than the other end. When the wind blows, it pushes the larger end in the direction that the wind is blowing TOWARDS, turning the lighter end in the direction that the wind is coming FROM. For example, in the basic weather vane arrow design, the arrow is at one end, with a larger tail at the opposite end. The wind will push the tail in the direction that the wind is blowing TOWARD, while the arrow will point to the direction that the wind is coming FROM.
Many weather vanes have directional markers beneath the arrow to make it easy to pinpoint the precise direction of the wind. If you are planning to add a weather vane to your own home, make sure to position it in the highest possible location. Avoid obstructions such as trees, buildings, or other structures that could interfere with the weather vane’s ability to accurately measure wind direction.
Measuring Wind Direction and Speed with a Windsock
Windsocks are a basic yet useful way to measure wind direction and speed. They point in the opposite direction from which the wind originates, so a windsock pointing south would indicate a northerly wind.
The advantage of a windsock is its ability to gauge the speed of a wind as well as its direction. Wind speed is measured by the angle of the windsock relative to its mounting pole. A 3.5 mph breeze is enough to properly orient the windsock to the wind direction, while stronger gusts of at least 17 mph will fully extend the windsock.
Measurements using Manual Methods
If you find yourself in a situation where instruments are unavailable, you may still be able to measure wind direction. To assess wind direction manually, wet your index finger and hold it up to the wind. The side that feels cool indicates the wind direction. Depending upon your location, you can also pluck a few blades of grass and drop them, letting the wind carry them away. The direction in which the grass drifts will indicate the direction of the wind.
US Department of Energy-Ask a Scientist
Weather Vane Pointing
Virginia Coastal Energy Research Consortium
Meteorological Instruments to Measure Wind Speed
US Department of Transportation
FAA Specifications for Wind Cone Assemblies