A few days ago I was contacted by David Brown from the Derby Hill Bird Observatory in Mexico, New York, USA. This location description may look a bit confusing to European eyes, but it is easy to find on the map: The observatory is located on the eastern shore of Lake Ontario in the state of New York.

David was counting migrating hawks as a part of his job, when a brief sunny period occurred during the otherwise cloudy morning on April 27th, 2025. This allowed him to catch a glimpse of a marvelous cirrus halo display, that would otherwise have gone completely unnoticed. He took pictures with an iPhone 15 Pro Max at around 10:10am EDT. The solar elevation was about 42.9° at that time.

A short video clip can be found here: https://youtu.be/VpgkhUm_258

The pictures show very well developed column crystal halos such as the circumscribed halo, parhelic circle, infralateral arc on the right-hand side, and a very pronounced Wegener’s anthelic arc. It is indeed remarkable how sharp the halos look, indicating small crystal tilts and large crystal faces (to reduce blurring by diffraction).

We can also see a weak 22° halo and 22° parhelia, as well as 120° parhelion on the right hand side (especially in the video). The presence of the latter two halo species reveals that a fraction of plate crystals must also have been present in the cirrostratus clouds.

Similar to the last post on this blog, there is a brightening of the parhelic circle at the anthelic point. From the observer’s standpoint, it is straightforward to label it as “anthelion”, even though theory argues that it might just be the superposition of the parhelic circle and Wegener arc branches.

David has stated that he has never seen something like this before. Cirrus halo phenomena of such a quality might indeed be a once-in-a-lifetime sighting, even if you pay close attention to the sky. Personally, I’m still waiting for my own bit of luck. Meanwhile, there are the diamond dust displays to enjoy in winter…