University of Minnesota
University of Minnesota
http://www.umn.edu/
direction

Wind direction is the direction from which the wind is blowing. It is shown in degrees measured from true (geographical) north, in a clockwise sense.

Both 0 and 360 are north, which produces the drastic jumps from near 0 to near 360 as the wind fluctuates a little to the east or west of north.

Wind direction is an instantaneous measurement, and therefore extremely variable. Shown here is a running 2 hour mean.

speed

Instaneous wind speed is recorded every 10 minutes. The left hand y-axis is in meters/sec, the right is miles per hour.

Wind measured over water is commonly expressed in knots (kts), which is equal to 1 nautical mile per hour or 1.125 statute (land) miles per hour.

1 m/s ~ 2.2 mph ~ 2.0 kts

vector

In this plot, the local wind speed and direction are shown as a vector comprised of eastward (u) and northward (v) components.

The scale of the vectors is shown in the figure. The horizontal time axis is not to the same scale as the 2 above.

In this figure, the arrows point in the direction the wind was blowing. Compare this to the wind direction shown in the top figure.