Noctilucent clouds are rare, high-altitude clouds that form in the mesosphere, about 50 miles above the Earth's surface. They are composed of ice crystals and are typically visible during twilight when the sun is just below the horizon. These clouds appear as glowing, bluish-white wisps and are most commonly seen in polar regions during summer months. These clouds are thought to be influenced by climate change and may become more frequent as temperatures rise. Their formation requires specific conditions, including very low temperatures and the presence of water vapor, making them a unique atmospheric phenomenon that intrigues scientists and skywatchers alike.