Iridescent clouds are a diffraction phenomenon caused by small water droplets or small ice crystals individually scattering light.
It is likely that atmospheric dust loading from increased comet and volcanic activity is contributing to the 'strange skies' we are witnessing, the cooling effect of which causes ice crystals to form. See also:
- Huge 'alien ship' cloud appears over Maracaibo, Venezuela
- Beautiful iridescent clouds appear over Santiago, Chile
- 'Rare' noctilucent clouds put on sunrise show over Whitley Bay, UK
- Rare atmospheric 'crown flash' phenomenon seen above Moscow, Russia
- What causes iridescent clouds?
- Rare undulatus asperatus clouds form over Dorset, UK
- Spectacular multi-colored 'light pillars' illuminate skies in northern China
- Ball-lightning? 'Strange light' seen over Canberra, Australia
- Weird glowing light spotted over Netherlands: plasma discharge event?
As they say how wonderful it is with their small water droplets. It looks like water runoff from an oily street.