Glories: effect of droplet size

Fig. 1 Glory for monodisperse drops

Fig. 2 Glory for disperse drops (5% SD)

Raymond Lee used "Lee diagrams" to examine the behaviour of primary and secondary rainbows. MiePlot allows users to generate Lee diagrams for other scattering angles, such as 170° - 180° to permit investigation of the glory, as shown in Fig. 1.

Fig. 1 is based on scattering calculations for 200 values of radius r between 5 µm and 20 µm, using the "High" option for the number of wavelengths (between 500 and 1,000 wavelengths). It shows that the glory consists of circular rings around the anti-solar point. 

• For r = 5 µm, the inner red ring has a radius of 4° from the anti-solar point (i.e. at 176°) with a further red ring at 7° radius (near 173°). 

• For r = 20 µm, the inner red ring at 1.3° radius (178.7°) with a further red ring at 2° radius (178°). 

The fine vertical stripes in Fig. 1 indicate significant variations between "adjacent" values of radius. Fig. 2 shows that these stripes disappear when the diagram is recalculated assuming that the drop sizes have a Log-Normal distribution with a standard deviation of 5%.