Iridescent Waves Over the White Mountains
March 16, 2008
The photo above showing iridescence in wave clouds was taken near Nashua, New Hampshire on November 17, 2007. Altocumulus clouds will often show irisation (the color exhibited by iridescent clouds), when positioned close to the Sun. On this autumn day, conditions were just right for wave clouds to form and to be thrust upward by the approximately 6,000 ft (1,829 m) summit of the White Mountains, a little to the north of my location. These variegated wave clouds were beautiful and persisted for several hours. It was phenomenal to behold these ripples of pastel colors. Iridescence is caused by diffraction of sunlight around minute water droplets of various sizes. The droplet size strongly affects the color that's displayed by the clouds.