mother-of-pearl cloud
Học thuậtThân thiện
Definition
Noun: A mother-of-pearl cloud is a specific type of cloud that appears luminous and displays iridescent colors, similar to the inside of a pearl oyster shell. It forms at very high altitudes in the stratosphere and is typically visible during twilight, when the sun is slightly below the horizon, illuminating it from below.
Usage
This term is a technical and descriptive name for a rare meteorological phenomenon. * The sighting of a mother-of-pearl cloud is a rare event for most observers. * Scientists study mother-of-pearl clouds to understand atmospheric conditions in the stratosphere.
Advanced Usage
- These clouds are formally known as nacreous clouds or polar stratospheric clouds (PSCs). The term "mother-of-pearl cloud" is a direct, descriptive translation of their visual appearance.
- Their formation is linked to extremely cold temperatures in the stratosphere, often over polar regions in winter.
Variants and Related Words
- Nacreous cloud (noun): The formal scientific synonym.
- Polar stratospheric cloud (PSC) (noun): The formal scientific term that categorizes these clouds by their location and composition.
Synonyms
- Nacreous cloud
Notes on Meaning
- The term is highly specific and refers only to this iridescent, high-altitude cloud type. It is not a general term for any colorful cloud.
- The iridescence is caused by the diffraction of sunlight through tiny, uniformly sized ice crystals.
Noun
- a luminous iridescent cloud at a high altitude that may be seen when the sun is a few degrees below the horizon