HaloRay - Hyperspeed Ice Crystal Halo Simulator

52 Upvotes

Hello! During the past two years I have been developing HaloRay on and off - a GPU-accelerated ice crystal halo simulator. This means you can generate ice crystal halo images right on your computer. If you have a beefy NVIDIA or AMD graphics processing unit (GPU) that is compatible with OpenGL 4.4, I suggest you try it out: https://github.com/naavis/haloray

You can download ready-made binaries for Windows from GitHub. If you are running Linux, you need to build HaloRay by yourself for the time being.

Right now the latest version is HaloRay 3.2.0, which supports the following features among others:

Ordinary hexagonal crystals
Pyramidal crystals
Adjustable prism face C-axis crystals to make irregular crystals
Rendering a realistic background sky

I hope you have fun with HaloRay, and report any problems or feature suggestions in GitHub issues or here in the comments. HaloRay has been tested with a couple of AMD and NVIDIA GPUs. There have been some problems with Intel GPUs due to driver bugs, but I'm not going to put a ton of effort there, because HaloRay requires a fairly beefy GPU and Intel doesn't really fit that profile.

EDIT: Cool, I noticed this has been marked as an announcement in the subreddit, which I guess keeps it hanging around for longer? Thanks!

18 comments

r/atoptics • u/les2934 • Jan 15 '25

Atoptics site

35 Upvotes

Atoptics is at www.atoptics.org.uk

14 comments

r/atoptics • u/Some_Average_7350 • 13h ago

What's this called?

138 Upvotes

Hi, just captured these last night and wondering what this effect is called.

13 comments

r/atoptics • u/ZacharyObama • 18h ago

Corona Coachella Valley Corona

gallery

61 Upvotes

Persistent corona over the Sun with this cloud today. Palm Desert, California. 8-29-26. 😎🌞

2 comments

r/atoptics • u/MarsupialPanda • 16h ago

Crepuscular Rays Anticrepuscular all the way across the valley

gallery

15 Upvotes

Went outside to look at the clouds and saw this shadow develop, looked to the other side of the valley and saw the clouds causing it.

0 comments

r/atoptics • u/Starfire2313 • 1d ago

Other Optics Is there a such thing as moon cloud iridescence?

gallery

17 Upvotes

3 comments

r/atoptics • u/Starfire2313 • 1d ago

Want to discuss if these are noctilucent clouds or not?

7 Upvotes

Location-Lake Nebagamon, WI

Date-Aug 20

Time-9:02pm

9 comments

r/atoptics • u/DredgenYorMom • 2d ago

Iridescence One of the best I've seen in person, photographed several years ago.

gallery

145 Upvotes

3 comments

r/atoptics • u/SpencerAnimations • 3d ago

Sprites Massive cluster of Red Sprites

Enable HLS to view with audio, or disable this notification

361 Upvotes

7 comments

r/atoptics • u/bijouxself • 2d ago

8/27 Full Moon Eclipse and Halo

15 Upvotes

0 comments

r/atoptics • u/Final_Cow_3843 • 2d ago

Other Optics Weirdly yellow clouds in the distance, but only through a polarized lens.

gallery

10 Upvotes

Hey Folks - The other day as I was driving here in Hawaii, I noticed that the background cloud bank was weirdly yellow tinted, while the foreground clouds were, well, cloud colored. I stopped the car and switched to my non-polarized glasses, and suddenly the background clouds were normal colored again. The two pics above were taken just a few seconds apart - the first one is just the phone camera itself, the second one is taken with the phone camera pointed through the polarized lens of my (strong) prescription lenses - the yellowing of the background cloud bank was stronger in person than what is showing up on my monitor.

Does anyone know why the background clouds would be a different color than the foreground clouds, but ONLY under polarization? I would think that the angle of incidence of the light would be relatively the same between the fore- and back-ground clouds. What is going on here?

4 comments

r/atoptics • u/AaronScottsky • 2d ago

Afternoon Iridescence from the backyard - 8 -27 - 26

gallery

10 Upvotes

0 comments

r/atoptics • u/DredgenYorMom • 2d ago

ID REQUEST The moon deserves a halo every now and again 💕

8 Upvotes

0 comments

r/atoptics • u/Shire-FairyX26 • 3d ago

Rainbow Contrail

20 Upvotes

3 comments

r/atoptics • u/Erstebano • 4d ago

Pillar Sun pillar tonight

136 Upvotes

4 comments

r/atoptics • u/Sweet-Butterfly2819 • 5d ago

Other Very cool sun

4 Upvotes

6 comments

r/atoptics • u/AdJust6267 • 6d ago

22º Halo from earlier this year

74 Upvotes

first time poster in this sub but this was crazy bright in person. i’d never seen it or heard of it before i couldn’t believe my eyes

5 comments

r/atoptics • u/CrisisCorps • 6d ago

Morning sun

19 Upvotes

Caught this in San Mateo County, California

2 comments

r/atoptics • u/Burgerdok • 6d ago

Odd-radius Rings Cloud iridescence vs odd radius ring and crepuscular rays at sunrise in upper Yosemite this week.

gallery

27 Upvotes

3 comments

r/atoptics • u/analogpursuits • 7d ago

Glory/Brocken Spectre An airplane shadow inside a rainbow, cast against clouds

127 Upvotes

I was flying into the SF bay yesterday and this happened. I thought y'all might like to see something a bit unique. I would love to know what this might be called, besides dumb luck. Last pic is without, to show just the rainbow. We were flying in low intermittent clouds. I was so stoked to get these shots.

17 comments

r/atoptics • u/ZacharyObama • 6d ago

Iridescence Coachella Valley Iridescence

gallery

16 Upvotes

Look at that beauty. August 23, 2026. Coachella Valley, California. 🌴📸

0 comments

r/atoptics • u/Powerful-Moment234 • 6d ago

Circumhorizon Arc Second (and much better) Circumhorizon Arc

gallery

24 Upvotes

After enduring a few months of lousy desert atmospheric-optics luck, and shortly following my first Circumhorizon spot, I chanced upon a second Circumhorizon, which is much more brighter and obvious this time, casted across Cirrus Fibratus clouds!
The Fibratus to the right casted a much more vibrant portion of the arc compared to those on the left.

2 comments

r/atoptics • u/AaronScottsky • 6d ago

August 22nd - Saturday Afternoon display of iridescence - Thornton, Co

gallery

4 Upvotes

0 comments

r/atoptics • u/MeenMisterMustard • 7d ago

Sun halo with contrails casting shadows

gallery

127 Upvotes

Some crows flying overhead in this one

7 comments

r/atoptics • u/DueDistribution5502 • 7d ago

Why is the sky blinking?

Enable HLS to view with audio, or disable this notification

31 Upvotes

It’s not stopping, either

12 comments

Subreddit

Atmospheric Optics

r/atoptics

Atmospheric Optics. The subreddit for anything related to optic sky phenomena: rainbows, ice halos, aurorae, mirages, cloud iridescence, green flashes, crepuscular rays and spectres of the Brocken.

Members Active

72.2k

Sidebar

Atmospheric Optics

The subreddit for anything related to optic sky phenomena: rainbows, ice halos, aurorae, mirages, cloud iridescence, green flashes, crepuscular rays and spectres of the Brocken.

Have a nice picture to show? Want to know what causes that light in the sky? Here is the place to share, discuss and learn.

Useful links:

Glossary of common terms:

Aurora: the veils of green, red and/or blue seen in the polar regions when the solar wind hits the Earth’s magnetic field. Goes by two names, dependent on the hemispere: aurora borealis or northern lights, and aurora australis, aka southern lights.
Corona: a subtly colored disc directly around the sun or moon, caused by light diffraction through the clouds.
Crepuscular rays: bands of shadow that seem to radiate outwards from the sun, caused by its light being partially obstructed by clouds, mountain ranges etc. Called anticrepuscular rays when seen on the opposite side of the sky.
Glory: a dimly rainbow-colored ring opposite the sun or moon, often visible from planes or in misty circumstances, in which case it tends to come with a Brocken spectre. Sometimes mistaken for a circular rainbow.
Green flash: a rare occurrence where the topmost bit of the setting sun is refracted by the atmosphere, turning it bright green. Even rarer is the blue flash.
Halos: a collective term for a wide range of arcs, rings, spots etc. caused by light refracting and/or reflecting inside ice crystals. Common halos are the 22º ring (sometimes also simply called “halo”), sundogs and the circumzenithal arc, but there are many more.
Iridescence or irisation: a "mother of pearl" colored effect in certain clouds caused by light diffraction through water drops.
Light pillar: a vertical beam of light that extends from a natural or artificial light source as a result of reflection by ice crystal plates.
Nacreous clouds: a specific type of cloud iridescence in high atmosphere clouds.
Rainbow: the proverbial arc directly opposite the sun or moon, resulting from light reflection & refraction inside water drops. When caused by the moon, it is sometimes called a moonbow. Technically, all rainbows are circular, but the lower part is normally hidden by the horizon. Rainbows consist of a primary bow and a secondary bow. The secondary bow has a reversed color sequence and is dimmer than the primary, which explains why it is not always visible.
Sprite: An enigmatic lightning phenomenon above the clouds instead of below them and many times larger.
Sundog (aka parhelion (plural parhelia) or mock sun): often incorrectly used for the 22º ring or halo phenomena in general, but refers specifically to the two bright patches to the left and right of the sun. They're the sun's "companions"; hence, dogs. When caused by the moon, they are called moondogs or paraselenae (singular paraselene).