The latitude range takes in Northern America, Canada and Northern Europe. Very few populated land masses exist at the corresponding latitudes in the southern hemisphere. Generally NLC will be seen close to the sunward horizon, perhaps extending to around 15 - 20 degrees above the horizon, along the twilight arch. Similarly, at local midnight, the NLC is poorly illuminated and the cloud sheet, if present, will recede closer to the horizon. Colour is generally white or a distinctive pearly-blue tone, sometimes with a golden lower edge.
Structure is reminiscent of daytime cirrostratus formation.
A representative selection of photographs can be viewed from the images page. At times high cirrus cloud can appear to be brighter than the twilit background, especially when a bright moon is present or local light pollution problems are extreme. Bright displays of NLC are quite unmistakable and can be an awe-inspiring sight. The Astronomer' magazine provides rapid publication of provisional NLC reports each summer. Various astronomical and meteorological Journals are also worth keeping an eye on for news of NLC research.