Imaged in Finland by Marko Mikkilä on the night of July, 31-1st August.
©Marko Mikkilä, shown with permission.
The bright noctilucent clouds extend from the northern horizon to well past the zenith.
The close-up below reveals their characteristic ribbed and skein-like structure.
The clouds, 80-85 km high (50-53 mile) high in the mesosphere, are composed of sub micron sized ice crystals. The clouds shine by scattering high altitude sunlight.