One of the graphics used in wind research is the wind rose – it visually depicts the direction and average speed from a given direction. The most useful graphic is a 3-dimensional or colour coded wind rose composed of Weibull distributions.
Shown Above: A Wind Rose with Weibull Distribution
By looking at this wind rose graphic, many pieces of information are instantly available. The overall length of a given bar indicates how much wind comes from a given direction. The length of the bar is composed of the composite of all readings of all wind speeds taken from that direction. Looking at this wind rose, it becomes obvious that the majority of prevailing wind in this location is from the southwest. It’s also relatively easy to observe that the majority of wind speeds recorded in that direction fall between 5 and 15 meters per second. There are almost no wind readings from the north and north east at this location, however there seems to be one outlying reading, from due East.
This wind rose would initially appear to be for a site that would be quite promising for wind power as there are many readings that fall within the operational parameters of a turbine, and they all come from a relatively tightly grouped direction, meaning the turbine should not have to continuously yaw back and forth looking for wind. Having this wind rose in hand while standing at the proposed site of the turbine would be an invaluable aid, as you could face in the direction of the best wind, look for local obstructions such as trees, buildings, or other obstacles (such as small hills, silos, barns, etc.) that could cause wind shade, turbulence, and poor performance. If the view to the south and west is clear, your research on the wind for this location would be pretty much complete!