Which way does the wind blow at the north pole?

The North and South Poles are special points on the Earth, because they are singularities of our coordinate system. All directions from the North Pole can be called South, because they are directed exactly away from the North Pole. The directions of North, South, East and West lose the meaning they have elsewhere on the Earth.

Nonetheless, if you were positioned there, you would not notice any difference from anywhere else on Earth (except it is quite cold, and there are very few trees ;)). If, as is quite likely, there is a wind, it comes from a definite direction, which may be from your front, your right hand or your left.

So the wind has a definite direction, even at the Poles, and the only problem is communicating the direction in an unambiguous way. The only way is to report the angle made by the wind with respect to an agreed upon direction. Away from the poles, by international agreement, winds are reported in Degrees True, i.e. the angle made by the wind vector across the unique circle of longitude passing through the measurement point. But there is no single, unique circle of longitude passing through the poles; there are an infinite number of them. For unambiguous reporting of direction, some particular one of them must be specified. By international agreement (WMO Manual on codes v. 1, Code Table 878), within one degree of the North Pole, the Greenwich (0 degree) meridian is used.

I.e. by international agreement, within about 60 nautical miles of the North Pole, winds are reported according to a compass face, oriented so the "North" arrow points toward the 0 degree meridian, and in this restricted area, "North" no longer refers to the North pole, but to the observatory in Greenwich, England. Our programs that convert wind vector data from the computer models to geographical coordinates follow this convention, and a wind flag oriented at 075 degrees at the pole means the wind is approaching from the direction of Washington, DC :).

Curiously, we have not been able to find an international standard concerning reports from the South Pole, which has a similar problem, even though there is a weather station at the South Pole but not at the North Pole. The South Pole station in practice uses the compass face aligned with "North" in the direction of the Greenwich meridian, and that is what we do within one degree of the South Pole.

Dr. Albion Taylor

Modified: September 23, 2008
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