Marco Meniero is an Italian astrophotographer, scientific sky photographer, and science communicator. Active since the 1990s, he is recognized as a leading expert and specialist in the observation, photographic documentation, classification, and physical explanation of atmospheric optics and photometeors.

Marco Meniero is an Italian astrophotographer, scientific sky photographer, and science communicator. Active since the 1990s, he is recognized as a leading expert and specialist in the observation, photographic documentation, classification, and physical explanation of atmospheric optics and photometeors.

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www.meniero.it @ All Rights Reserved 2021 - Website created by Flazio Experience

www.meniero.it @ All Rights Reserved 2021 - Website created by Flazio Experience

PHOTOMETEORS

ATMOSPHERIC OPTICAL PHENOMENA

PHOTOMETEORS:

According to the World Meteorological Organization’s definition, as set out in the *International Cloud Atlas*, a photometeor is an optical phenomenon produced by the reflection, refraction, diffraction, or interference of light from the Sun or the Moon.

The official WMO classification includes various optical phenomena observable in the atmosphere, such as:

Halo phenomena: solar and lunar halos and related phenomena.

Phenomena produced by water droplets: rainbows, coronae, and glories.

Cloud-associated phenomena: iridescence.

Atmospheric refraction phenomena: mirages and optical shimmering.

Other luminous phenomena: the green flash, twilight colors, and crepuscular rays.

This classification is documented in the *International Cloud Atlas*, the WMO’s international reference for the classification of clouds and other meteorological phenomena.

Reference sources

WMO — International Cloud Atlas: Photometeors - WMO — International Cloud Atlas: Classification of photometeors.

Atmospheric Optics — Les Cowley: atoptics.co.uk - San Diego State University — Andrew T. Young: Atmospheric Optics.

ATMOSPHERIC OPTICAL PHENOMENA

An atmospheric optical phenomenon is a broad concept: it is a visual manifestation resulting from the interaction of electromagnetic radiation—primarily sunlight or moonlight—with the constituents of Earth's atmosphere, such as gas molecules, water droplets, ice crystals, and aerosol particles. Its formation may involve various physical processes, including the refraction, reflection, scattering, diffraction, and interference of light. Variations in the air's refractive index can also produce optical effects, such as mirages and the apparent distortion of the solar or lunar disk.

It encompasses a wide range of phenomena, from the blue color of the sky and the reddening of the Sun at sunset to rainbows, halos, coronae, glories, and mirages.

Reference sources

Atmospheric Optics — atoptics.co.uk - Walter Tape and Andrew T. Young — Atmospheric Optics, San Diego State University: - World Meteorological Organization (WMO) — Official WMO website:

ATMOSPHERIC OPTICAL PHENOMENA
↳ PHOTOMETEORS
↳ OTHER atmospheric optical phenomena (enrosadira, atmospheric refraction…)

Therefore: All photometeors are atmospheric optical phenomena, but not all atmospheric optical phenomena are photometeors.

GENERAL RULE

☁️ Cloud with droplets → diffraction, refraction and reflection → coronas, glories, etc …

☁️ Cloud with ice → ice crystals → geometric refraction/reflection → halos, sundogs, 

     arcs, light pillars

🌧️ Raindrops → refraction + internal reflection + dispersion → rainbow

Which CLOUD for which PHENOMENON?

• CIRRUS → halos
• CIRROSTRATUS → large halo systems
• ALTOCUMULUS/ALTOSTRATUS → coronas and iridescence 
• FOG → fogbow, glory
• ICE CRYSTALS → pillar, sundogs, arcs, arcs

Solar halo
Lunar halo
Solar corona
Lunar corona
Cloud iridescence
Glory
Rainbow
Fogbow
Bishop's Ring
Mirage (atmospheric optical phenomenon)
Shimmer (atmospheric optical phenomenon)
Scintillation (atmospheric optical phenomenon)
Green flash (atmospheric optical phenomenon)
Twilight colors (atmospheric optical phenomenon)
Crepuscular rays

THE 15 PHOTOMETEORS ACCORDING TO

THE CLASSIFICATION OF THE

World Meteorological Organization PSUM

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ITALIAN OPTICAL PICTURE OF THE DAY

GREEN FLASH

Green segment  - Green rim 

Blue rim -Red rim

Green spikes - Green flash - Green ray

Blue flash -Red flash 

Green flash su macchie solari

Mock Mirage

The IOPOD consists in periodically awarding the image of a photometeor and posting it online with a technical-scientific explanation accessible to all

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CLASSIFICATION BASED ON PHYSICAL CAUSES:

REFRACTION

REFLECTION

REFRACTION 

+ 

REFLECTION

• pillars (light columns)
• parhelic and subparhelic circle
• circles
• crosses 
• subsundog 
• 120° parhelia
• anthelic arc
• anthelic pillar   
• rare phenomena

• 22° halo and 46° halo
• circumscribed halo
• tangent arcs
• supralateral and infralateral arcs
• circumzenithal arc
• circumzenithal arc
• tangent arcs, Parry arcs
• Lowitz arc and rare arcs
• sundog 

• rainbow
• fogbow
• red rainbow

• Learn more

• Learn more

• Learn more

ATMOSPHERIC REFRACTION

DIFFRACTION

SCATTERING

• sky colors
• crepuscular rays
• anticrepuscular rays
• cloud colors
• colors of the Sun and the Moon
• Enrosadire (Alpenglow)

• coronas and iridescence
• glory
• Brocken spectre
• Opposition Effect

• scintillation
• mirages
• Fata Morgana
• green flash
• shimmer
• Flying Dutchman 

• Learn more

• Learn more

• Learn more

RECOGNIZE THE PHENOMENON

IS IT REALLY A

PHOTOMETEOR?

Is there a circle around the Sun?

→ Halo or Corona

Are there bright spots on either side of the Sun?

→ Parhelia or sundogs

Do you see a horizontal rainbow that looks like a smile?

→ It is a circumhorizontal arc if it is low,

→ It is a circumzenithal arc if it is at the zenith

Do you see a column of light above or below the Sun or Moon?

→ Pillar

Do you see iridescent colors in the clouds?

→ Iridescence

Do you see a green flash at sunset, or a green rim

on the Moon?

→ Green flash

Do you see a rainbow without distinct colors?

→ Fogbow

Do you see your shadow cast from a peak onto the fog below?

→ Brocken spectre; if it is surrounded by a colored

halo, there is also a Glory

Do you see a ship (or an island) reflected downwards?

→ Inferior mirage

Do you see a ship flying in the sky?

→ Flying Dutchman

Not sure what you observed, or photographed?

Send the photo and I’ll tell you what optical phenomenon it is

•  meniero@gmail.com

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TEXTS

REFERENCES

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