Rare Clouds: Noctilucent Clouds

The rare cloud of today is the Noctilucent Cloud. These clouds are actually the highest clouds in the atmosphere at altitudes of 47-53 miles. Since they are so high in the atmosphere they are made from tiny ice crystals. The cloud is seen only if it is high enough in the atmosphere to reflect light from the sun. Sunlight from the lit side of the earth reflects off of the high altitude clouds, which makes them visible. (Check out the illustration to the left for clarification)

The word Noctilucent can be roughly translated to mean "night shining" in Latin, which is proven true as the clouds are seen "shining" at night. The clouds are seen most often during the summer months at latitudes between 50° and 70°. The formation of the clouds is said to be a notification of changes in the upper atmosphere. Noctilucent clouds are a recently discovered weather phenomenon and no observations were recorded before 1885