The marvels of water drops and water crystals

The marvels of water drops and water crystals Responsible for rain, snow, rainbows, Halo and glory Measuring water droplets Glory Rainbow Halo The concept of “maximum deviation” The concept of “minimum deviation”

How to monitor the size of a water droplet as it growth or evaporates? Through whispering gallery modes

H. C. Bryant and N. Jarmie, “The {Glory}", Scientific American, 231: 60— 71 (1974) Other application: monitoring the growth of water drops in clouds (more spaced resonances) Monitoring the evaporation of a large droplet The successive narrow peaks are separated by 1/100 wavelengths, indicating that they correspond to resonances of 100 cycles. Backscattered intensity TIME

The Glory A complete description of the glory involves not only the whispering gallery resonance, but also the fact that the backscattering is issued from multiple light » rings « (the annular edge of the droplets), which interfere with each other. Simulation: Make negative

Rainbow The concept of “maximum deviation”

What happens to a narrow beam irradiating a water sphere? Maximum deviation angle The retro-refraction angle varies from zero to a limit angle qlim

Max Int Irradiation by an extended beam Maximum intensity around the maximum deviation angle.

Double rainbow

The Halo Related to the minimum deviation of water crystals

A q 1 q 2 q 3 p-A d q 4