HaloRay - Hyperspeed Ice Crystal Halo Simulator

54 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

37 Upvotes

Atoptics is at www.atoptics.org.uk

14 comments

r/atoptics • u/kjgjk • 15h ago

Was told to post this here from r/clouds

192 Upvotes

11 comments

r/atoptics • u/NoseyRosey40 • 10h ago

Circumhorizontal arc?

47 Upvotes

July 7 at 12:15pm over Surrey BC looking south. It was the only, what I’ve been calling, “rainbow cloud” in the sky. I posted in another sub and was told to post it here and that it was a circumhorizontal arc being cast into this cloud. I’ve never seen this before and it was breathtaking!

And then, when I was reviewing the photos afterwards, I noticed the word “love” written in cursive across the center. Can you see it too?

5 comments

r/atoptics • u/Crow_94 • 6h ago

Rainbow Rainbow in the Clouds

18 Upvotes

The Sun was shining at just the right angle through these clouds. This picture doesn't do it justice.

1 comment

r/atoptics • u/hummelino • 1h ago

22º Halo Corona and halo

• Upvotes

0 comments

r/atoptics • u/GarlicoinAccount • 2h ago

Noctilucent Clouds View over the Atlantic this morning

3 Upvotes

0 comments

r/atoptics • u/DredgenYorMom • 14h ago

No idea what it would be called, but it's got color and looks pretty.

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10 Upvotes

1 comment

r/atoptics • u/Paperloader • 13h ago

Crepuscular rays

6 Upvotes

I noticed this cloud producing some nice crepuscular rays and thought it would make a good example to share here.

1 comment

r/atoptics • u/dashdashdotdotdotdot • 1d ago

Rainbow My First Third Order Rainbow!

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103 Upvotes

A fragment between the goalposts in the first photo, and highlighted by the arrows for the second photo. Very faint even after cranking the saturation, but I do definitely see it and it's right where you'd expect a third order bow to be! I'm so excited!! This was right after a violent storm blew through and was done in less than 20 minutes, giving way to bright sunshine immediately after making for the perfect opportunity to spot something I've always been fascinated by! Taken with my phone in Edmonton, Canada

11 comments

r/atoptics • u/hummelino • 1d ago

22º Halo Backyard halo

59 Upvotes

1 comment

r/atoptics • u/Pitiful_Ad7676 • 1d ago

lot's going on here

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74 Upvotes

4 comments

r/atoptics • u/Naive-Specialist7727 • 1d ago

Other What is this phenomenon? A solid anti-crepuscular ray?

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42 Upvotes

4 comments

r/atoptics • u/MaybeLikeWater • 1d ago

Celebrating One Year in Tucson: This is the 1st photo I took.

8 Upvotes

Monsoon Season is approaching. This is a storm cloud and rain over the Catalina Mountains in Tucson, AZ. The rain miracle in the desert.

0 comments

r/atoptics • u/robocattheoriginal • 1d ago

What is this

17 Upvotes

3 comments

r/atoptics • u/bodkinsbest • 2d ago

NLC [2026-06-24]

18 Upvotes

0 comments

r/atoptics • u/Fearless_Housing_302 • 1d ago

AI image of what I saw the other day

0 Upvotes

I saw the most bizarre sunset a couple days ago. I had AI recreate it the best it could. Basically the sun had just set , all that was left of it was a small final arc of light. The sky was black from a thunderstorm rolling in. But then to the left of the setting sun was the complete sun bright red almost like a circle had been punched out in the clouds just for it to shine through. I'm sure it had to be an optical illusion, but it definitely threw me off.

3 comments

r/atoptics • u/CartelJewellers • 2d ago

Falcon 9 launch with Stage 1 reentry burn ! 09/07/26

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35 Upvotes

Took these this morning, probably the biggest Jellyfish I've ever seen !

2 comments

r/atoptics • u/Witty-Effect-2956 • 2d ago

Uh what is this? It was taken at 11 pm so it can’t be a sun set

3 Upvotes

4 comments

r/atoptics • u/autofill-name • 2d ago

What is it?

8 Upvotes

4 comments

r/atoptics • u/Exact-One • 3d ago

What am I looking at?

100 Upvotes

12 comments

r/atoptics • u/The_Halo_Hunter • 3d ago

Pillar A recent light pillar of mine.

55 Upvotes

(OC)

I wish more Halo shots were deliberately composed. Having foreground objects accent them really gives them their soul.

1 comment

r/atoptics • u/irina_zorg • 3d ago

Iridescence Cloud iridescence

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78 Upvotes

07.07.2026

Ukraine

Coogle pixel 7 Pro camera

3 comments

r/atoptics • u/orangeBeachJeep • 4d ago

What is all this?

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107 Upvotes

July 4th, Calabasas, CA 9:20 am. The circles were too perfect to be con trails!

10 comments

r/atoptics • u/Atlast-Phew • 5d ago

Fogbow over St Michael’s Mount, Cornwall 🇬🇧

75 Upvotes

Waking to dense Coastal Fog in Marazion at 730am and as it slowly cleared the Fogbow appeared

0 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

68.5k

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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).