Interpreting the Wind Rose
Interpreting the Wind Rose.
The concentric circles (two green, one red) are the speed scale, indicating 10, 20 and 30 knots respectively.
The green crosshairs indicate the 4 compass points. "Up" is North. The local magnetic variation is included,
and the white "MN" indicates Magnetic North.
The green marker tick, indicated with "TN" is true north.
The solid white line represents the alignment of the runway itself, and is identified at either end with the
two-digit runway identifier, eg "32".
At the bottom right is the date and time the image was created. Note, the time is in UTC (Zulu)
Wind data is sampled several times per minute, and the last hour is shown.
Across the bottom left of the image is a time-scale. 0m is "now". 15m (in green) is 15 minutes ago. 30m (in
cyan) is 30 minutes ago etc. The colours change gradually from white through yellow, green, blue, violet and red
indicating the time scale. The vertical position of the line (distance from the bottom of the screen) indicates
the relative wind speed. This gives a visual gauge if the wind is increasing or decreasing and how gusty it is.
Finally, the really useful bit. Each sample (typically several hundred) is plotted on the rose. A marker in the colour
representing the age of the wind sample is plotted at the actual direction and speed, overlaying the display.
From this, wind is immediately conveyed at a glance. You can tell the speed and direction of the wind, how
variable it has been and how that relates to the airstrip alignment.