Wind Roses

No, they are not flowers that grow in windy places. A wind rose is the most common way to display statistical information about the relationship between wind speed and direction at a particular site. Basically the frequency of occurrence of winds from different directions is calculated from a dataset, and then a polar plot is constructed (similar to a bar graph) with length out from the center proportional to relative frequency. This allows a simple visual portrayal of the most common (or rare) wind directions. Just remember that meteorological convention always designates wind direction according to the direction that the wind comes from. Within each of the resulting "pie slices" of the wind rose, the relative frequency of different wind speeds may be indicated by areas of different color, similar to a "stacked" bar chart.

Wind roses are used in many applications, such as wind energy development, sailing, and air quality management.

Here is an example of a wind rose showing the winds observed at Miscou Island, New Brunswick, Canada during June 2007:



Software for creating wind roses from raw data files is available from Lakes Environmental (free) and EnviroWare. Precalculated wind roses for many U.S. stations are available online through the Natural Resources Conservations Service. More discussion and examples are available here.