Cloud Corona and Iridescent Colors
Photographer: Marco MenieroSummary Author: Marco Meniero
Featured here is a beautiful cloud corona I captured above Civitavecchia, Rome Italy, on May 14, 2024. Iridescent colors depend on the diffraction of very small particles that are slightly larger than the wavelength of the light they diffract. The light is deflected several times, and the resulting pastel colors vary from blue to green and from yellow to red. Coronas have spherical shapes around their light source (most often the Sun or Moon), while the iridescences are irregular and often frayed, appearing as crowns.
Coronas are made up of a series of colored circles superimposed on each other or separated, with a radius varying from a few minutes of arc to approximately 10 to 13 degrees. Higher order rings with variable saturations can also be seen. They can transform into iridescences with irregular colors if the rings fray; in these unusual cases, the phenomenon can be seen up to 45 degrees from the Sun.
The rings take on the colors of the spectrum with red towards the outside, unlike halos which have red on the inside. Clouds that generate the coronas must be thin and semi-transparent. Generally, the water droplets composing them (in some cases, ice crystals) are of similar size to each other, which occurs more frequently in newly formed clouds.
Solar coronas may be difficult to spot because the light from the Sun can dazzle the observer; often the use of good dark glasses (grey-blue lenses are recommended) facilitates vision. However, polarized lenses do not improve visibility because the polarization effect is only evident when the Sun at least 60 degrees from an iridescent cloud.
Civitavecchia, Rome Italy Coordinates: 42.1007, 11.7830
Related Links:
Cloud Corona over the Sierra Nevada
Marco's Website
Featured here is a beautiful cloud corona I captured above Civitavecchia, Rome Italy, on May 14, 2024. Iridescent colors depend on the diffraction of very small particles that are slightly larger than the wavelength of the light they diffract. The light is deflected several times, and the resulting pastel colors vary from blue to green and from yellow to red. Coronas have spherical shapes around their light source (most often the Sun or Moon), while the iridescences are irregular and often frayed, appearing as crowns.
Coronas are made up of a series of colored circles superimposed on each other or separated, with a radius varying from a few minutes of arc to approximately 10 to 13 degrees. Higher order rings with variable saturations can also be seen. They can transform into iridescences with irregular colors if the rings fray; in these unusual cases, the phenomenon can be seen up to 45 degrees from the Sun.
The rings take on the colors of the spectrum with red towards the outside, unlike halos which have red on the inside. Clouds that generate the coronas must be thin and semi-transparent. Generally, the water droplets composing them (in some cases, ice crystals) are of similar size to each other, which occurs more frequently in newly formed clouds.
Solar coronas may be difficult to spot because the light from the Sun can dazzle the observer; often the use of good dark glasses (grey-blue lenses are recommended) facilitates vision. However, polarized lenses do not improve visibility because the polarization effect is only evident when the Sun at least 60 degrees from an iridescent cloud.
Civitavecchia, Rome Italy Coordinates: 42.1007, 11.7830
Related Links:
Cloud Corona over the Sierra Nevada
Marco's Website