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Crepuscular ray 1 hour after sunset

On September 12th Claudia Hinz observed the sunset from the 1835m high Wendelstein Observatory.

At 19.18 CET (Daylight saving) the sun disappeared behind a 250 km distant thunder cloud over the Black Forest, Schwarzwald, in South Eastern Germany. Then the sun would have been ~2° above the astronomical horizon. The sea level horizon was 197 km distant and dipped 1.4°.

At around 20.00 sheet lightning was noticed on the horizon.

At 20.15 a 30° long crepuscular ray was formed by the thundercloud. At that time, nearly an hour after sunset, the sun was 8° below the astronomical horizon. The ray was faint but clearly seen over the remaining twilight colours. The image was made with a 150mm lens and a 4s exposure.

Alder corona with iridescence and cloud rays

The 27th of March was in a manner of speaking one of our first warm days this year. Owing to the long and cold winter together with the abrupt change the plants exploded into life and produced a very strong pollen concentration in the air. The humidity was very low and so the resulting pollen coronae stood out against the dry sky. The coronae originated from from alders which are very common in the area (Barsinghausen, near Hannover). Hazel were also flowering at that time but would have made a different form of corona.

That day Reinhard Nitze took very unusual pictures of the alder coronae. On the one hand the coronae were intense but appeared together with another phenomena, e.g. with iridescence clouds or cloud rays. Sometimes, however, Reinhard saw them “undecorated”.