windroos

Wind rose, or windroos in Dutch, is a graphical representation used to summarize how wind speed and direction are distributed at a location over a specific period. The plot is circular, oriented to the compass, and divided into directional sectors (commonly eight or sixteen). For each sector, the frequency or duration of winds from that direction is shown, often using petals or bars whose length or color corresponds to wind speed.

Data for a wind rose are obtained from weather stations or remote sensing, with measurements typically logged hourly, daily, or monthly across the chosen period. The diagram may use wind speed bins (calm, light, moderate, strong) and either petal lengths or colored segments to indicate frequency or duration.

Windroses are used in wind resource assessment for energy projects, in architectural and urban planning to evaluate natural ventilation and microclimates, and in aviation and marine applications to understand directional wind conditions. They can also support climatological analyses by summarizing long-term wind patterns.

Construction involves selecting directions, grouping wind speeds into bins, calculating the share of time from each direction in each bin, and plotting the results on a polar chart. Variants include monthly windroses for seasonal patterns and wind-speed distribution plots or probability plots derived from the same data.

Limitations include dependence on data quality and station location, the potential masking of temporal variability when aggregating over long periods, and the fact that a wind rose describes historic conditions rather than predicting future winds.