Wind
Wind[edit]
Wind direction is defined as the true direction from which the wind originates at a given location. It is always reported as the direction the wind is coming from rather than the direction it is moving toward. For example, wind blowing from the north toward the south is called a north wind.
Wind direction is measured in ten-degree increments, clockwise around the compass:
- East: 90°
- South: 180°
- West: 270°
- North: 360°
- A value of 0° is used only when the wind is calm.
Wind Barbs[edit]
Wind barbs are a visual tool for representing wind speed and direction. The shaft shows the wind’s direction (with the barbed end pointing to where the wind is coming from), while the barbs and pennants indicate speed in knots:
- Each short barb = 5 knots
- Each long barb = 10 knots
- Each pennant = 50 knots
- Calm wind = a large circle drawn around the sky-cover symbol
Although wind speeds are plotted in 5-knot increments, the ranges themselves are somewhat uneven. For practical purposes, it is easiest to round to the nearest 5 knots, which aligns with the average value of each range. Be careful not to confuse knots with miles per hour—rounding in miles will produce inaccurate results.
Reading Wind Barbs[edit]
Distinguishing between 5-knot and 10-knot barbs can be tricky. A 5-knot barb is often drawn slightly inboard of the shaft, forming a small fork or “Y” shape. A 10-knot barb, by contrast, connects at the end of the shaft, forming a clearer “L.” Comparing multiple barbs on the same chart can also help you spot the difference.
A helpful way to visualize a wind barb is to imagine it as an arrow: the barbed end resembles feathers, while the opposite end is the arrowhead (sometimes drawn with a circle). In this way, the “arrow” points in the direction the wind is moving.