The rare clouds that glow in the dark are called noctilucent clouds.
Understanding Noctilucent Clouds
Noctilucent clouds, also known as polar mesospheric clouds, are the highest clouds in Earth's atmosphere. These clouds are fascinating because they are visible only under specific conditions and exhibit a unique glowing appearance.
Key Characteristics:
- Rarity: According to the reference information, noctilucent clouds are "extremely rare."
- Visibility: They are typically seen in the night sky during clear, summer nights.
- Appearance: Their appearance is usually bluish or silvery, and they become visible around the same time as the brightest stars.
- Altitude: They are extremely high clouds, existing in the mesosphere.
Conditions for Formation and Visibility
Noctilucent clouds require very cold temperatures (around -120 to -130°C) and the presence of water vapor to form. These conditions are typically found at high altitudes during summer months. The "glowing" effect is due to sunlight reflecting off ice crystals that make up the clouds, even when the sun is below the horizon.
Where to See Them
While rare, noctilucent clouds are most often observed at latitudes between 50° and 70° north and south of the equator. Best viewing times are usually around twilight, after sunset or before sunrise.
Summary of Noctilucent Clouds
| Feature | Description |
|---|---|
| Name | Noctilucent Clouds |
| Rarity | Extremely Rare |
| Appearance | Bluish or Silvery |
| Visibility | Clear, Summer Nights |
| Altitude | Very High (Mesosphere) |
| Formation | Requires very cold temperatures and water vapor |
| Best Viewing | Twilight, between 50° and 70° latitude, after sunset or before sunrise |
