NASA Highlights 'Fire Rainbow' Phenomenon Over West Virginia
NASA's Astronomy Picture of the Day featured a circumhorizontal arc, popularly known as a 'fire rainbow,' captured near North Fork Mountain in West Virginia. The visual phenomenon relies on specific solar angles and horizontally aligned ice crystals in high cirrus clouds.
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30-second brief
NASA's Astronomy Picture of the Day featured a rare 'fire rainbow' captured over West Virginia. The phenomenon occurs when sunlight refracts through horizontally aligned ice crystals in high-altitude cirrus clouds.
One-minute read
NASA featured a circumhorizontal arc, colloquially referred to as a 'fire rainbow,' as its Astronomy Picture of the Day. Photographed by Christa Harbig near North Fork Mountain in West Virginia, the phenomenon presents flame-like colors parallel to the horizon. The atmospheric effect happens when sunlight enters flat, hexagonal ice crystals in cirrus clouds, acting as prisms that bend sunlight uniformly. For the arc to be visible, the Sun must reach an elevation of at least 58 degrees above the horizon, and the ice crystals must be horizontally aligned, making the sight relatively unusual.
Why this matters
Understanding atmospheric optics helps clarify how light interacts with ice crystals and clouds in Earth's atmosphere, offering insights into atmospheric physics and weather phenomena.
Background
Astronomy Picture of the Day (APOD) is a service provided by NASA and Michigan Technological University that features a different image of the universe or Earth's atmosphere daily, accompanied by a brief explanation written by a professional astronomer.
Key terms
- Circumhorizontal arc
- An atmospheric optical phenomenon formed by the refraction of sunlight through horizontally oriented ice crystals in cirrus clouds.
- Cirrus cloud
- A high-altitude cloud composed primarily of ice crystals, often appearing thin and wispy.
Structured analysis built only from the verified reports behind this story.
AI analysis based on reports from science.nasa.gov. Not original reporting.
Key facts
- NASA featured a circumhorizontal arc, colloquially referred to as a 'fire rainbow,' as its Astronomy Picture of the Day.
- Photographed by Christa Harbig near North Fork Mountain in West Virginia, the phenomenon presents flame-like colors parallel to the horizon.
- The atmospheric effect happens when sunlight enters flat, hexagonal ice crystals in cirrus clouds, acting as prisms that bend sunlight uniformly.
- For the arc to be visible, the Sun must reach an elevation of at least 58 degrees above the horizon, and the ice crystals must be horizontally aligned, making the sight relatively unusual.
Key numbers
- 58
- For the arc to be visible, the Sun must reach an elevation of at least 58 degrees above the horizon, and the i
NASA’s Astronomy Picture of the Day featured a circumhorizontal arc, commonly known as a "fire rainbow," captured over West Virginia, United States. Photographed near North Fork Mountain by photographer Christa Harbig, the phenomenon displays vibrant, flame-like colors running parallel to the horizon across a thin cirrus cloud layer.
A circumhorizontal arc is an atmospheric optical phenomenon created when sunlight refracts through floating ice crystals within high-altitude clouds, such as cirrus fibratus. The numerous flat, hexagonal ice crystals composing the cloud act as small prisms, collectively bending light in a similar direction to form a bright spectral pattern across the sky.
Specific geometry is required for this visual effect to take place. The Sun must be positioned at least 58 degrees high in the sky, and the ice crystals within the cirrus cloud layer must be aligned horizontally. Because these distinct conditions must coincide, circumhorizontal arcs are relatively uncommon to observe.
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Reported by 1 verified source· 1 verified outlet
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- 2 Aug, 04:05
- Latest update
- 2 Aug, 04:05
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- science.nasa.gov
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NASA Highlights 'Fire Rainbow' Phenomenon Over West Virginia
science.nasa.gov
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science · nasa · astronomy · atmosphere · optics
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