Atmospheric
Optics
NLCs, Oxfordshire, England
A capture by Mary Spicer in the early hours of the morning of 4th July '16. The early morning of 6th July saw even more extensive clouds (below).
Noctilucent clouds are Earth's highest at 80-85km (50-53mile) high and a few km below the mesopause, the coldest part of the atmosphere. Paradoxically, as climate change warms the surface and lower atmosphere, the mesosphere cools and NLCs become more frequent.
Tiny, 0.1 micron ice crystals make them. They shine by scattering high altitude sunlight.
Recognise them by their characteristic ribbed, skein-like structure. Binoculars show a sharp structure compared to lower cirrus.
The display of 6th July.
Meteor debris
may provide many nuclei for the growth of ice crystals at the mesopause. The tangled smoky appearance of these clouds make this quite believable.
