Atmospheric effects

This page is devoted to atmospheric effects. All photographs presented in this section have been taken by the authors with digital DSLR, mirrorless, compact and analog cameras. For some sunrise or sunset images, relatively long focal lengths have been required, like telescopes.

WARNING : Never view the sun through optical instruments like telescopes or binoculars without reducing light intensity with appropriate filters. Irreversible eye damage may result!

· Sunrise over La Neuveville and the lake Bienne.	· Sunrise from Prêles with a lonely Venus.

Wonderful sunrise observed from the small town of La Neuveville (BE, Switzerland) on January 20, 2021. Samsung Galaxy S10 (SM-G973F). Exp 1/316s, 6mm, f/2.4, ISO 50, UTC 7:07. © Michel Willemin	Lonely Venus in the morning sky of December 19, 2020, observed from Prêles (BE, Switzerland). Canon EOS R + RF 24-105mm f/4 L IS USM. Exp 1/8s, 91mm, f/6.3, ISO 400, UTC 6:35. © Michel Willemin

· Sunrise behind the Schreckhorn (4078m), observed from Prêles (BE, Switzerland) on December 27, 2020.

Sunspots are clearly visible, as well as a thin green flash. Canon EOS R + EF 400mm f/5.6 L USM. Exp 1/2000s, f/25, ISO 100, UTC 7:32. © Michel Willemin
The Schreckhorn is one of the most difficult summit of the Bernese Alps and also the highest mountain fully located in the Canton of Bern.
Press clipping: SpaceWeather.com of December 27, 2020. Journal du Jura

of December 29, 2020. Gismeteo.ru of December 30, 2020.

· Collection of images taken during the same sunrise, including also an animation.

Still pictures: Exp 1/8000, 1/8000, 1/1250, 1/1250s, f/16, 16, 18, 25, ISO 100, UTC 7:26, 7:28, 7:29, 7:31, respectively. © Michel Willemin

· Sunrise on the Bernese Alps observed from Prêles, Switzerland on January 5, 2020.

Canon EOS M6 + EF 400mm f/5.6 L USM. Panorama Exp 3x 1/800s, f/11, ISO 400, UTC 7:18. © Michel Willemin
Press clipping: Journal du Jura

of January 22, 2020.

· Collection of images taken during the same sunrise.

Exp 1/1000, 1/4000, 1/4000, 1/4000s, f/11, 11, 11, 18, ISO 400, UTC 7:24, 7:26, 7:27, 7:27, respectively. © Michel Willemin

· Sunset observed from the Croatian island of Lošinj and offering a tiny Green Flash!

July 19, 2019, from Otok Lošinj direction Otok Unije (Croatia). © Michel Willemin

· Rainbow, sundog and sunrise observed from Prêles, Switzerland

Respective publications in Journal du Jura on July 27, 2017, on October 14, 2017 and on January 6, 2018.

· Eruptive sunrise over the Schreckhorn (4078m) observed from Prêles, Switzerland

· Sundogs

Parhelia or sundogs are the brightest and most common halo that originates in an oriented crystal. They are found on either side of the sun at the same altitude and tend to show bright colors. They are red on their sunward side and fainter and more bluish away from the sun. At low altitudes parhelia are found 22° from the sun but at higher altitudes they separate from it.

The second image has been taken just before the sunset, which explains the red dominent. Third shot: Samsung Galaxy S10, Marin (NE), Switzerland on May 17, 2021, UTC 16:55.

· Rainbows "theory"
This very interesting, natural and nice effect is due to the refraction and dispersion of the light through the water drops. Sun and rain together is the condition for rainbows. The primary rainbow is easy to observe. It results from a single internal reflexion and two refraction of the light of the sun in water drops. The index of refraction of water depends on the wavelength (dispersion), which produces a decomposition of the light during the two refraction processes, like a prism. Under good conditions, a secondary rainbow can also be observed (see second photograph). In this case, two internal reflexions of light within the water drops occur. The intensity of the secondary rainbow is much lower than for the primary or main rainbow.

*Wavelength (nm)*	*Index n*	*Primary angle (°)*	*Secondary angle (°)*
300	1.3532	38.72	56.80
350	1.3501	39.66	55.26
400	1.3440	40.51	53.73
450	1.3411	40.91	52.99
500	1.3364	41.27	52.33
550	1.3344	41.64	51.68
600	1.3335	42.01	51.02
650	1.3318	42.25	50.58
700	1.3309	42.38	50.34
800	1.3294	42.60	49.92
900	1.3285	42.73	49.70
1000	1.3277	42.86	49.49