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Ursa Astronomical Association
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Ursa Astronomical Association

Corona - 11.1.2022 at 10.30 - 11.1.2022 at 11.30 Juva Observation number 103707

Visibility V / V

Petri Martikainen, Ursa (Itä-Suomi)

In the morning there was a sharp 25 degree frost and a nice fog in the sunny landscape. Hence to chase fog phenomena. However, the fogs were a bit disappointing, and when the car's brakes were freezing at times, I decided to return to my home. As I was approaching the hill of the village, I was able to witness a phenomenon I had never seen before. Above the field opening on the northern slope of the hill hovered very thin clouds of clouds low, which the Sun, shining behind the hill, dyed into intensely colored clouds of color. Some of the clouds were just above the tops of the trees, almost "at a distance of contact," and the impression was very three-dimensional. And what colors shone in the clouds! I tried to record what I saw on the camera, but it was challenging. Even the tripod had stayed home, so I sometimes had to pick it up so I could shoot the video. However, the best moment had already passed and the video had to be shot with a spare camera, the lens of which had not been cleaned. Images are cropped but otherwise unprocessed in random order, and video is accelerated to twice the speed. Last is a picture of the ring left over when the color cloud show ended.

I guess thin clouds only formed on the spot as the wind blowing from the southwest brought moist frosty air over the hill. The Koikkala hill rises almost a hundred meters above the surface of Lake Saimaa. The north slope of the hill was also several degrees colder than the side of the sunshine. In young clouds, the droplets are the same size as each other, allowing colors to appear. Although it appears in the pictures that the clouds are high in the sky, in reality they were no more than 50-100 meters above the ground.

Additional information
  • Lightsource of the phenomenon
    • Sunlight
  • Common atmospheric phenomena
    • Corona info

      Corona (of the sun) is a colored ring or series of rings visible in the immediate vicinity of the light source. It can appear in both clouds and fog.

      Coronae are formed in very small drops of water. The size of the droplets affects the size of the corona ring. The smaller the droplets on average, the larger the circle is.

      With the water droplets being about the same size as each other, a series of strongly colored corona rings can be seen in the sky. When the droplet size is wide, only one ring with faint colors is visible.

      A corona can also be formed by small ice crystals in the upper clouds, but such coronas are very faint.

      The corona phenomena identification in Skywatch is intended for different kinds of corona rings that appear around the Sun. The coronae of the moon and planets have their own phenomena identification selections.

      Unlike halo rings, which are located apart from the Sun or the Moon, the perimeters form a uniform field of light in the immediate vicinity of the celestial body.

      Corona. Image by Ismo Luukkonen.

      Corona in the morning mist. Photo by Iida Pennanen.


      The distortion of the corona is caused by changing droplet sizes in the cloud. Imabe by Eetu Saarti. 

      A solar corona on a thick cloud. The lack of colors and suble changes in shades is hinting about wide range of droplets in different sizes. Photo by Marko Riikonen

      Feeble vaque corona. Image by Matias Takala.


      If the size of the droplets changes drasticly, the corona may appear strongly distorted. Photo by Aki Taavitsainen.

    • Iridescent clouds
Comments: 2 pcs
Timo Alanko - 11.1.2022 at 19.05 Report this

Upeita kuvia! Toimivat miltei kadonneiden helmiäisten korvikkeena :)

Petri Martikainen - 12.1.2022 at 21.34 Report this

Kiitos! Kuvat eivät tee oikeutta sille, miltä nuo näyttivät livenä. Välillä tuli kieltämättä myös helmiäiset mieleen.

Lentelin samana aamuna dronella useammassakin paikassa, taisi tulla oma pakkasennätys. Hyvin se toimi, mutta kun lensin lopulta 26 asteen pakkasessa sumuun kuvaamaan sumukaarta, niin linssi oli hetkessä täysin huurussa ja jäätä kertyi myös propelleihin.

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