Noise roses

A noise rose indicates whether it is more (graded red colors) or less (graded green colors) noisier then normal. The radius of the rose indicates the distance between the source at the center of the rose and a receiver point at the compass angle. To keep it simple for weather maps, the sound weather is given for ranges of distance and angle. Figure 2 uses a distance step of 200 m and an angle step of 30°. The message of the noise rose in Figure 2 is clear: There is a favorable sound propagation to the east, typically the result of westerly winds at day time.

Figure 2 – Noise rose

The discussion of the change of noise roses during a night time inversion will show that noise roses are normally more complex than the noise rose in Figure 2. Time lines of noise roses provides an insight into the influence of refraction of sound rays due to wind and temperature and its interaction.