There has been some discussion about NLCs being seen in the night sky recently. Also known as 'noctilucent clouds'. These are the highest clouds in the sky and are typically seen in our night sky in latitudes of 50 - 65 degrees. Noctilucent means 'night shining'.
NLCs are colourless or bluish-white clouds and can be skein-like, rich with undulations and corrugations, knots and streaks, clawing upwards into the night sky, or at other times they can lie close to the horizon as a featureless band.
NLCs are seasonal and can be seen between mid May and mid August in the northern hemisphere, mid-November to mid-february in the Southern Hemisphere). They are never visible in daylight. Wait until an hour after sunset when twilight has deepened. The sun should be 6 - 16 degrees below the horizon, enough to darken the sky but not so low that the NLCs are not still in sunlight. Firstly, search low in the sky towards the direction of the sun beneath the horizon, northwest before midnight, northeast afterwards.
Binoculars can help in distinguishing them from lower cirrus clouds. They appear sharper under magnification.
NLCs are can sometimes visible further south, having been sighted in Europe as far south as Austria, Hungary, Italy and southern Germany. In the USA they have been seen in Utah and Colorado.
Luckily for me, I was driving home across the Peak District on the morning of June 24th around local 1am. This is the darkest time of the night though the night sky never gets totally dark on the distant northern horizon at this time of year.
The photos on this page show views across Chesterfield, showing the NLC clouds on the northern horizon. These were taken on Beeley Moor, above the villages of Upper Loads and Holymoorside. This part of the moor is approximately 1100 feet above sea level.
The camera used was a small black one! ;0)