Chapter 16, Problem 1GST

To determine

The particles that are usually associated with each of the optical phenomena, such as rainbows, halos, coronas, glories, and sun dogs.

Answer to Problem 1GST

The particles that are associated with the formation of rainbow are raindrop, halos, and sundogs, which are icecrystals, and the coronas and glories, which are cloud droplets.

Explanation of Solution

The formation of rainbow occurs when light gets refracted, internally reflected, and then refracted again as it passes through a raindrop. In a primary rainbow, the reflection of sunlight occurs once within a raindrop, whereas it is reflected twice within a raindrop in a secondary rainbow.

The formation of halos is caused by the four basic types of hexagonal ice crystals, such as plates, columns, capped columns, and bullets. Since the formation of halos results in the formation of ice crystals, they generally have a random orientation and the diffused light forms a nearly circular halo that is centered on the illuminating object such as the Sun or Moon.

Coronas are formed when a thin layer ofaltostratus or cirrostratus clouds veils the illuminating body. When the droplets that results in the formation of coronas are tiny and uniform in size, diffraction more effectively separates the white light source into the colors of the rainbow.

The formation of the sundogs also occur under the same conditions as, and in conjunction with, halos. The only difference is that their existence depends on the presence of many vertically oriented ice crystals. This particular orientation occurs when elongated ice crystalsslowly descend.

The formation of glories occur when light is backscattered in a manner similar to rainbows. However, the cloud droplets that are responsible for glories have a size much smaller and more uniform than the raindrops,which results in the formation of rainbows.