NLC
Noctilucent clouds are tenuous cloud-like phenomena in the upper atmosphere of Earth. They consist of ice crystals and are only visible during astronomical twilight. They are most often observed during the summer months from latitudes between ±50° and ±70°. They are visible only during local summer months and when the Sun is below the observer's horizon, but while these very high clouds are still in sunlight. They are the highest clouds in Earth's atmosphere, located in the mesosphere at altitudes of around 249,000 to 279,000 feet. They are too faint to be seen in daylight, and are visible only when illuminated by sunlight from below the horizon while the lower layers of the atmosphere are in Earth's shadow.
NLC
Noctilucent clouds are tenuous cloud-like phenomena in the upper atmosphere of Earth. They consist of ice crystals and are only visible during astronomical twilight. They are most often observed during the summer months from latitudes between ±50° and ±70°. They are visible only during local summer months and when the Sun is below the observer's horizon, but while these very high clouds are still in sunlight. They are the highest clouds in Earth's atmosphere, located in the mesosphere at altitudes of around 249,000 to 279,000 feet. They are too faint to be seen in daylight, and are visible only when illuminated by sunlight from below the horizon while the lower layers of the atmosphere are in Earth's shadow.