At around 2 p.m. on February 23, 2016 I was filming superior mirage of a distant land and superior mirage of a sea surface. From San Francisco the superior mirages are observed on warm days, and February 23 was not an exception. The air temperature was higher than 70 degree Fahrenheit. At some point I took my eyes from the horizon and looked up. The sight amazed me. I was looking at bright, circular halos that I have never seen before. Later I found out that the halos I observed were 9 °, 18 °, 20 °, 24 ° and 35 ° radii, and 24 ° upper tangent arc. and that the display has a name: odd radius halos.
Pictures with a different methods of encroachment
From the pictures posted on the NET by other people I found out that a similar display was seen at Ballico, California, which is 50 miles (80 kilometers) east of San Francisco. Another observer was located in Sunnyvale 20 miles (32 kilometers) south of San Francisco. It often happens that odd radius halos are observed over vast distances. As a matter of fact on April 14, 1974 the odd radius halos display in England was overdosed at the locations that were 460 kilometers apart. From Claudia Hinz I’ve learned that odd halos display in Middle Europe are associated with prominent cold fronts that slowly move from north to south, but no cold front arrived in San Francisco on the next day. February 24, 2016 was only slighter cooler than February 23.
Author: Mila Zinkova, San Francisco