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   Fogbow to rainbow - Droplet size 

Fogbow to rainbow

As the droplet diameter (shown above in micron, 1/1000 mm) increases, the bow narrows and the inner supernumerary bows move closer together. Eventually, for raindrops larger than 1 mm diameter, diffraction effects become small and we have a rainbow with bright colours and hardly noticeable supernumeraries.

Cloud and fog droplets rarely exceed 100 micron diameter.  The bows intermediate in appearance from 100 - 500 micron dia. droplets are occasionally seen in the sprays of waterfalls.

The simulations used a lognormal size distribution with a standard deviation of 15%