11 Fathoms Up

The view from our front porch!

February Sunsets 2018

January Sunsets 2018

New Years Eve 2017

December Sunsets 2017

November Sunsets 2017

October Sunsets 2017

September Sunsets 2017

August Sunsets 2017

Thunderstorm 10-12-2017

Cloud Iridescence

This thunderstorm moved toward the setting sun, giving a prolonged display of Cloud Iridescence.

Cloud iridescence occurs as colors in a cloud similar to those seen in oil films on puddles. The colors are usually pastel, but can be very vivid. When occurring near the sun, the effect can be difficult to spot as it is blocked by the sun's glare. 

Iridescent clouds are a diffraction phenomenon caused by small water droplets or small ice crystals scattering light. Larger ice crystals do not produce iridescence, but can cause halos, a different phenomenon.

If parts of clouds contain small water droplets or ice crystals of similar size, their cumulative effect is seen as colors. The cloud must be thin, so that most rays encounter only a single droplet. Iridescence is mostly seen at cloud edges or in semi-transparent clouds, while newly forming clouds produce the brightest and most colorful iridescence.

© Ralph Arwood 2018