Noctilucent clouds are rare high-altitude clouds visible only under certain conditions. They form during the summer months and appear after sunset as delicate, wispy blue or silver streaks across the sky.
The name noctilucent is derived from the Latin words "nocto" and "lucent" which translates to "night" and "shining" respectively, according to Merriam Webster. They are sometimes referred to as polar mesospheric clouds.
