Photo of setting Sun. To the right there is brightened bit of airplane contrail, a parhelium (sundog). The sky is covered by thin cirrus cloud and there is another contrail visible.

Sun setting in Ore Mountains of Czech Republic. The little bright rainbowy cloud on the right is #sundog, or perhelion, the most common type of #icehalo, formed by refraction in airborne ice crystals, in this case it seems to form on a jet airplane contrail. #sunset

Photo from a ski slope in Italy with prominent diamond dust halo display.

Brilliant diamond dust halo display in Italy. The halos shown include 22° halo, parhelic circle (without sundogs!), upper tangent arc, suncave Parry arc and supralateral arc. #icehalo

Source: redd.it/1q2dx3n

An image of an ice halo around the moon in Taos New Mexico taken by Maggie Duval

#icehalo around the #moon #taosnewmexico

Looking up in the Manawatū tonite is quite the experience! #icehalo

Complex ice halo display with anomalous halos from pyramidal crystals.

Complex ice halo display with anomalous halos from pyramidal crystals.

Complex ice halo display with anomalous halos from pyramidal crystals.

Complex ice halo display from Pingxiang, China, taken on May 12. There are plethora of weird arcs and rings that come from pyramidal ice crystals. These are very rare sight in themselves, but ones this bright and complex are something very exceptional. #icehalo

Photo of a complex ice halo display with 22° halo, circumscribed halo, complete parhelic circle and the very rare Wegener arcs.

This image from Vietnam shows relationship of 22° halo, circumscribed halo (both centered on the Sun) and parhelic circle (centered on zenith). But what makes this really special is very clear Wegener arcs inside the parhelic circle. These are very rare. #icehalo

source: redd.it/1knac1d

Photo showing an upper tangent arc halo in Ústí nad Labem, Czech Republic.

Upper tangent arc just now as I am waiting for my train. #icehalo #atoptics

Photo of a ice halo display in Boyaca, Columbia featuring prominent circumscribed halo and significant part of parhelic circle. Faint 22° halo can also be seen. Unusually, there seems to be no trace of parhelia. Source: https://redd.it/1iso2z6

Beautiful ice halo display in Boyca, Columbia. The prominent rainbowy ring is actually not 22° halo, but circumscribed halo: note, how the ring isn't a circle but an oval. There's also fainter, but still quite clear parhelic circle: that's the white arc that intersects the Sun.

#icehalo

Night-time photo from a Scottish city, showing colorful light pillars each ending with a bifuraction that gives impression of a vaulted structure. These bifurcations are most likely upper tanget arcs, a type of ice halo.

Very interesting ice halo display from Scotland. What we see here are light pillars from city lights capped with what appears to be upper tangent arcs, with possible coincident suncave Parry arc. #icehalo #atoptics

Photo of a 22° halo with upper tanget arc, sundogs and subsun, all created on diamond dust. Photo from French Alps.

Beautiful diamond dust halo in French Alps. Source: redd.it/1i4jrnb

#icehalo #atoptics

Photo showing a bright circumzenithal arc with some dark spruce tree sillhouetes against a steel gray sky.

The photo doesn't show a rainbow. It's an example of atmospheric optics phenomena known as ice halos. They are not caused by sunlight refracting in water droplets like rainbows but in ice crystals and there's veritable menagerie of them. Let's have a 🧵 about them. 1/17
#icehalo #halos #atoptics

Ice Halo! An atmospheric phenomenon that involves light passing through ice crystals
#mspaint #icehalo #atmosphericphenomena #rainbow

Sun dog! #baltimore #baltimoreskies #sundog #icehalo #prisminthesky #🌞🐶 Photo taken at these ...

Sun dog!

#baltimore #baltimoreskies #sundog #icehalo #prisminthesky #🌞🐶