Noctilucent Clouds/Polar Mesospheric Clouds

Scientists refer to these types of clouds with two different names, depending on where the clouds are observed from. They are called Polar Mesospheric Clouds (PMCs) when they are viewed from space, and are called Noctilucent Clouds (NLCs) when viewed from Earth, typically from a location near the Earth's poles. Clouds that are associated with weather form in the troposphere. However, noctilucent clouds form very high up in the mesosphere - about 85,300 meters above the Earth's surface! They are likely made of frozen water or ice crystals. NLCs are seen best just after sunset as they glow an electric, beautiful blue-white (noctilucent actually means "night-shining").