photo #6777236

Simi Eliott, daughter of Mark Eliott (Member 47,785), saw a psychedelic light show above Ho Chi Minh City, Vietnam. This was an iridescent pileus cloud. The formation develops when the powerful rising air currents within a Cumulus or Cumulonimbus cloud force stable air above to lift upwards, causing it to cool as it does so. The moisture in this stable air can condense into droplets as it cools, creating a pileus accessory cloud perched on top of the cloud like a cap. When the water droplets in this pileus are very small and similarly sized, they bend, or diffract, the sunlight in a way that separates it into its component colours to create a shimmering, psychedelic iridescence. Groovy.