Every photographer at a sunset knows the pull of facing west. The horizon glows, the clouds catch fire, and everything that seems worth photographing appears to be directly in front of you. But experienced light chasers learn early to resist that pull: to pivot, scan the opposite sky, and sometimes find something even more remarkable waiting at the eastern horizon. Anticrepuscular rays are what happens when you finally turn around.
They look almost impossible: broad shafts of alternating light and shadow that seem to radiate from a single point on the eastern horizon at sunset, growing wider as they rise toward the zenith and then narrowing again as they descend on the far side. They are the mirror image of crepuscular rays, traveling the same path through the atmosphere but arriving, by trick of perspective, at the sky's opposite pole. You have almost certainly seen them without knowing what they were. Once you understand what you are looking at, you will never stand still at a sunset again.
What Are Anticrepuscular Rays?
Anticrepuscular rays, sometimes called antisolar rays, are beams of sunlight and shadow that appear to converge on the horizon directly opposite the sun. At sunset, that means they gather in the east; at sunrise, they collect in the west. The word itself is direct: "anti" from the Greek meaning opposite, and "crepuscular" from the Latin crepusculum, meaning twilight. They are the twilight rays that appear on the anti-sun side of the sky.
In practice they look like long, slightly curved bands of varying brightness stretching from directly overhead down toward the opposite horizon, where they appear to narrow toward a single luminous or darkened point. Sometimes the rays are pale and subtle, best seen with a slight squint. Other times, when the atmosphere is loaded with dust, smoke, or sea spray, they are bold enough to photograph with a phone. The most dramatic displays happen when the sun is near the horizon and the sky is partly clouded, the same conditions that produce a brilliant sunset on the other side of the sky.
The Science of Anticrepuscular Rays
To understand anticrepuscular rays, start with their more famous cousins. When the sun is near the horizon, clouds or elevated terrain can block portions of the light beam and cast long shadows through the atmosphere. Because the air always contains scattering particles, including water droplets, dust, pollution, sea salt, and pollen, the illuminated corridors between those shadows become visible as bright rays while the shadowed corridors appear darker. This is called volumetric scattering, and it is the same physics that makes a beam of light through a dusty window visible as a distinct column rather than a general brightening of the room.
Crepuscular rays appear to fan outward from the sun, which sits near the horizon. But those rays are not actually diverging. The sun is approximately 93 million miles from Earth, so its rays arrive at our atmosphere as essentially parallel beams. What makes them look like they radiate from a single point is perspective, the same geometric illusion that makes two rails of a perfectly straight railway appear to converge at the horizon. The rays are parallel, but the visual system, trained to interpret perspective depth, reads them as radiating outward from their vanishing point.
Now extend those parallel rays all the way across the sky. They enter the atmosphere from the western horizon at sunset, travel overhead, and continue to the opposite side of the sky. On the eastern side, perspective works in reverse: the parallel bands appear to converge again, this time toward a point on the eastern horizon called the antisolar point. That convergence, the apparent narrowing of parallel light and shadow bands on the far side of the sky, is what we see as anticrepuscular rays.
The antisolar point is defined as the point on the celestial sphere exactly opposite the sun, along the line from the sun through the observer's eyes extended outward. At sunrise and sunset, when the sun sits precisely at the horizon, the antisolar point also sits on the opposite horizon at the same altitude, zero degrees of elevation. As the sun climbs above the horizon, the antisolar point descends below it and is no longer visible. This is why anticrepuscular rays, like crepuscular rays, are a twilight phenomenon. The geometry is only favorable during the roughly sixty minutes around sunrise and sunset, when both the sun and its opposing point are close enough to the horizon for the ray bands to span a large enough arc of sky to be clearly visible and photogenic.
Why the Rays Appear to Curve
One of the most striking things about anticrepuscular rays is that they do not appear perfectly straight. As they arc from directly overhead toward the eastern horizon, they often seem to bow gently, following the curve of the sky dome rather than the straight-line geometry you might expect from parallel beams. This apparent curvature has two causes working together.
The smaller component is genuine atmospheric refraction: light bends slightly as it passes through layers of air at different temperatures and densities, and this bending affects the path of each ray by a small but measurable amount. The larger component is geometric projection. A straight line drawn through three-dimensional space, when projected onto the curved bowl of the sky as perceived by a viewer at the center, appears curved. Think of tracing a great circle route on a globe, then projecting it onto a flat map: it curves. When the parallel rays of the sun are perceived against the spherical dome of the atmosphere from within that dome, straight rays projected across large angular distances appear to follow arcs. The greater the span from overhead to the horizon, the more pronounced the apparent curvature becomes. If you were watching from space, above the scattering layer entirely, the rays would appear perfectly parallel. Only from inside the atmosphere does the perspective and projection combine to produce the spectacular fan-and-converge geometry we see at ground level.
The Connection to Crepuscular Rays
Anticrepuscular rays and crepuscular rays are literally the same rays. This is the single most useful fact for finding them in the field. If you see crepuscular rays, the dramatic God rays fanning out from behind clouds near the sun, then anticrepuscular rays are very likely also present if you turn 180 degrees and examine the opposite horizon. The shadows being cast by clouds or terrain near the sun are long enough, when conditions are favorable, to extend across the full arc of the sky to the opposite horizon.
The reason most observers have seen crepuscular rays many times but rarely noticed anticrepuscular rays is simple: attention direction. We face the spectacular sunset. The anticrepuscular rays, quieter and more understated, form behind us. They require a deliberate act of turning, of resisting the gravitational pull of the brightest and most colorful part of the sky. There is no app alert for them. No one in the crowd at a popular viewpoint turns and says look east. The photographer who finds them found them by choice.
Not every crepuscular ray display produces visible anticrepuscular rays. The rays must be bright enough and the shadows dark enough to remain distinguishable after traveling the full arc of the sky. A display with only one or two distinct rays near the sun may not produce detectable counterparts on the opposite horizon. But when the sky near the sun is filled with a broad fan of rays, the kind of scene that makes photographers stop mid-sentence, the opposite horizon almost always holds something worth the pivot.
Atmospheric Conditions That Favor Anticrepuscular Rays
Certain atmospheric states reliably improve both the frequency and the photographic quality of anticrepuscular ray displays.
Particle Loading in the Atmosphere
Volumetric scattering works better when the air contains more particles. After wildfire smoke drifts into a region, during periods of elevated humidity, after dust transport events, or near coastlines where sea spray raises atmospheric moisture, the air is more richly loaded and any rays become brighter and more visually distinct. Some of the most dramatic anticrepuscular ray photographs have been made downwind of major wildfires, where smoke can transform the entire sky into a scattering medium of extraordinary efficiency. Photographers living in the western United States, southern Europe, or Australia have documented this correlation repeatedly during fire seasons.
Cloud Structure Near the Sun
The shadows that create anticrepuscular rays originate near the sun, typically from towering cumulus or cumulonimbus clouds with well-defined edges, or from stratus layers with clear gaps. Smooth, unbroken overcast produces no distinct rays because there are no shadow-casting edges. Thin, wispy cirrus produces diffuse light rather than sharp shadows. The ideal is a partly cloudy sky with bold, discrete cloud masses in the western sky at sunset, casting long shadows that have enough contrast to remain visible across the full arc of sky to the eastern horizon.
Visibility to Both Horizons
Anticrepuscular rays converge at a point on the horizon. If your eastern horizon is obscured by haze, buildings, trees, or mountains, you may see the rays passing overhead but lose them before they reach their vanishing point. Open terrain, whether a coastline with open water to the east, a prairie, an elevated ridgeline, or an open plateau, gives the clearest view of the full convergence. The combination of an unobstructed horizon in both directions is what makes elevated viewpoints and coastal locations disproportionately valuable for this specific phenomenon.
Season and Latitude
At mid-latitudes, roughly 30 to 60 degrees north or south, the sun moves at a lower angle to the horizon at sunset during summer and early autumn than it does in tropical regions, where the sun sets steeply and the twilight window is short. A slower-setting sun spends more time near the horizon, giving the atmosphere more time to develop the scattering conditions that make rays visible. In northern hemisphere locations, the combination of summer thunderstorm activity generating large cloud masses and the extended twilight geometry makes June through September a productive season for anticrepuscular ray photography.
How to Find and Predict Anticrepuscular Rays
No dedicated app predicts anticrepuscular rays directly, because the cloud structure needed to generate them cannot be forecast with precision beyond a few hours. But you can build a reliable searching strategy from what is foreseeable.
Start with an app that shows the sun's compass bearing at golden hour. PhotoPills, The Photographer's Ephemeris, and SunSurveyor all give this information clearly. Note the bearing toward the sun at the moment of sunset and calculate the opposite bearing: add 180 degrees if the sun's bearing is less than 180, subtract 180 if it is greater. That opposite bearing is precisely where to direct your attention for anticrepuscular rays. If the sun sets at 255 degrees (slightly south of due west), the antisolar point is at 75 degrees, slightly north of due east.
Check cloud cover forecasts for the hours before your planned shoot. You want cloud development in the western half of the sky at sunset, not total overcast, but active cumulus or towering cells with defined structure. Apps like Windy display animated cloud layer forecasts that can help you assess whether shadow-casting clouds are likely to be in position. A completely clear sky produces beautiful sunsets but almost no crepuscular or anticrepuscular rays, because there are no clouds to cast shadows through the atmosphere.
Most importantly, whenever you are already positioned for a sunset and you see strong crepuscular rays fanning out from behind the clouds toward you, pivot immediately 180 degrees. You have roughly five to fifteen minutes before the geometry changes as the sun drops below the horizon. The opposite horizon is almost always worth the look, and the cost of checking is just a few seconds of attention.
Photographing Anticrepuscular Rays
Anticrepuscular rays reward photographers who plan for them deliberately rather than stumbling upon them at the last second. A small amount of preparation transforms the experience from occasional lucky capture to consistent intentional documentation.
Lens Choice
Because anticrepuscular rays stretch from directly overhead to the horizon, an ultra-wide angle lens is nearly essential for capturing the full fan and convergence in a single frame. On a full-frame sensor, focal lengths of 14 to 24mm capture the dramatic spread from zenith to horizon. On an APS-C crop sensor camera, 10 to 15mm achieves a similar result. Fisheye lenses, 8 to 10mm on APS-C or 15mm on full-frame, can capture an even wider swath of sky, and their barrel distortion will exaggerate the apparent curvature of the rays, a stylistic choice rather than an inaccuracy since the rays do appear to curve when viewed by the human eye.
If you prefer to isolate just the convergence point at the horizon, a moderate telephoto in the 70 to 135mm range can compress the perspective and emphasize the geometry of the bands narrowing to a single point. This is a fundamentally different compositional approach: instead of showing the full sweep of the sky, you are showing the vanishing point with maximum detail and compression. Both approaches are valid and produce very different images from the same scene.
Exposure and Camera Settings
Anticrepuscular rays form in sky that is already at golden-hour or early blue-hour brightness levels, typically ranging from two to three stops darker than the crepuscular side of the sky where the sunset is occurring. Expose for the rays themselves rather than for any ground subject. A starting point of ISO 400, aperture f/5.6, and 1/60 second captures sky detail in most displays without blowing the brighter bands. If the convergence point is darker than the surrounding sky, a display that shows a dark antisolar point rather than a bright one, reduce your exposure compensation slightly to preserve detail in the lighter bands flanking it.
Shoot in RAW format whenever possible. The subtle luminance contrast between lit and shadowed bands is exactly the kind of tonal information that RAW captures better than in-camera JPEG compression. In post-processing, lifting the clarity or texture slider on the sky region in Lightroom or Capture One consistently reveals rays that were barely detectable in the original preview. A gentle increase in dehaze also tends to improve visibility of the ray structure in the sky.
Filters
A circular polarizing filter reduces atmospheric haze and increases contrast between lit and shadowed bands in the sky. Rotate the polarizer while looking through the viewfinder toward the anticrepuscular zone: you will typically find a position that noticeably increases the visibility of the ray structure. Because you are facing away from the sun, you are not managing direct sunlight glare. You are using the polarizer to reduce Rayleigh scattering in the sky itself, which remains effective at angles away from the direct solar beam.
Graduated neutral density filters are less useful for anticrepuscular ray photography than for conventional sunset compositions, because the rays span from overhead to the horizon and a linear gradient does not align with their distribution across the frame. If you need to balance a bright foreground with the sky, a hard-stop graduated ND placed at the horizon can help, but most anticrepuscular ray compositions work best when the sky occupies the majority of the frame and is allowed to hold the full tonal range of the display.
Composition
The convergence point on the eastern horizon is your compositional anchor. Placing it roughly one third up from the bottom of the frame, per the rule of thirds, and allowing the rays to fan upward and outward toward the corners creates a natural radial composition that leads the viewer's eye from the image edges inward toward the vanishing point. This is geometrically satisfying in a way that is immediately legible even to viewers who have never consciously noticed anticrepuscular rays before.
Including a silhouetted element at the convergence point adds scale and grounds the abstract sky pattern in physical space. A distant lighthouse, a tree line on the horizon, a city skyline, a pier, or a mountain profile placed at the antisolar point gives the viewer something to anchor to. The contrast between a sharp, dark silhouette at the vanishing point of the rays and the spreading fan of light above it is one of the most visually powerful compositions possible from this phenomenon.
On coastlines or open water, look for the reflection of the rays in calm water below the horizon. On very still mornings or evenings, the convergence point and the fan of bands above it can be mirrored below in the water, creating an hourglass or diamond shape centered on the horizon. This reflected convergence is rarely photographed, because it requires both the calm water and the observer facing away from the sunset at the precise moment when conditions align.
The Mindful Practice of Turning Around
There is a broader teaching in anticrepuscular rays that extends well past photography technique. Every sunset draws a crowd to face west. The drama, the color, the obvious beauty, it is irresistible. We face it fully, we raise cameras, and we leave the remaining 300 degrees of sky largely unexamined. Anticrepuscular rays exist only for those who resist that magnetic pull and turn in the unfashionable direction.
Mindfulness teachers sometimes speak of beginner's mind: approaching familiar experiences as though encountering them for the first time, without the filter of assumption and habit. At a sunset, beginner's mind means genuinely not knowing in advance where the most interesting light will appear. It means looking east when everything in the environment says to look west. It means standing for a moment with your back to the spectacle and asking: what is here that I have been missing, not just today but every time I have stood at a sunset?
The window for anticrepuscular rays is brief, usually ten minutes or less at the peak of the display. This brevity has its own instruction. You cannot wander off and return when you feel ready. You either give the full sky your full attention within this narrow window, or the moment closes without you. There is something clarifying about real constraints. The light chaser who tracks both crepuscular and anticrepuscular rays simultaneously is fully present in the way that only a specific, time-limited, high-attention task can produce. It is not concentration for its own sake; it is concentration made genuinely urgent by the irreversibility of the light.
Try this practice at your next golden-hour session: set a quiet timer to fire every three minutes during the last thirty minutes of sunlight. When it sounds, turn 180 degrees from wherever you are pointing and spend thirty seconds scanning the opposite sky before returning to your primary subject. You will miss fewer anticrepuscular displays. Over time you may also notice that the habit of structured looking, of periodically checking the direction you assumed had nothing to offer, shapes how you move through the world on ordinary days in contexts that have nothing to do with photography.
Notable Locations and Conditions for Anticrepuscular Ray Photography
Because they are less well known than crepuscular rays, anticrepuscular rays are underrepresented in photographic archives. But the displays that have been carefully documented are genuinely spectacular and point toward location types that reliably produce strong results.
The great plains of North America, including the central regions of Kansas, Nebraska, and the Dakotas, produce some of the most dramatic displays documented by storm photographers. The combination of completely open flat terrain extending to an unobstructed 360-degree horizon, abundant summer thunderstorm activity generating enormous cloud masses with sharp edges, and moisture-laden prairie air creates conditions for extraordinarily long and distinct ray systems. Storm chasers positioned near developing supercell thunderstorms at sunset have documented both crepuscular and anticrepuscular rays simultaneously in full-sky panoramas, the rays appearing to form a complete arc from horizon to horizon through the zenith overhead.
Coastal locations with open water to both east and west are among the most reliable locations globally for this phenomenon. The absence of terrain obstruction in any direction means the full convergence is visible, and maritime air provides the particle loading that makes rays bright. Elevated coastal headlands are particularly valuable: the combination of height, which provides a clear view to a low horizon in every direction, with maritime air quality and the typically active cloud structure over coastal waters makes for a high success rate on favorable evenings.
Mountain viewpoints positioned above a valley fog layer offer a variant of the phenomenon that is worth specifically seeking. When low cloud or radiation fog fills a valley and higher-altitude cumulus simultaneously casts shadows, the illuminated fog layer itself becomes the scattering medium for anticrepuscular rays of unusual density. Because liquid water droplets scatter light differently from dry aerosols, these fog-layer displays are often warmer in tone and more luminous than the same display seen over open land. Valley fog forms reliably on clear, calm autumn nights after a warm day, and dissipates by mid-morning, making the narrow window around sunrise the specific target for this variant.
Frequently Asked Questions
What is the difference between crepuscular rays and anticrepuscular rays?
Crepuscular rays appear to radiate outward from the sun when you face toward it at sunrise or sunset. Anticrepuscular rays are the same beams of light and shadow traced in the opposite direction, converging on the horizon directly opposite the sun. Both are caused by parallel bands of illuminated and shadowed air passing through a particle-laden atmosphere. The only difference is the direction you are facing when you observe them: toward the sun for crepuscular rays, away from the sun for anticrepuscular rays.
Why do anticrepuscular rays appear to converge at a single point?
The sun is so far away that its rays arrive at Earth as essentially parallel beams. Parallel lines in perspective, however, appear to meet at a vanishing point, which is why railway tracks look as though they converge at the horizon. When you face the sun, the vanishing point is the sun itself, making crepuscular rays appear to radiate outward. When you face away, the vanishing point is the antisolar point on the opposite horizon, and the same parallel rays appear to converge there for exactly the same geometric reason.
How rare are anticrepuscular rays?
They are less frequently photographed than crepuscular rays, but mainly because most observers face the sun and never check the opposite sky. When strong crepuscular rays are visible, anticrepuscular rays are very often present simultaneously. Make a habit of scanning both sides of the sky at every golden-hour session and you may see them several times a month in locations with regular afternoon cloud activity and reasonable atmospheric particle loading.
What is the antisolar point and where is it in the sky?
The antisolar point is the spot on the celestial sphere exactly opposite the sun, on the line from the sun through your eyes extended to the far side of the sky. At sunrise and sunset, when the sun sits on the horizon, the antisolar point also sits on the opposite horizon at the same altitude. As the sun climbs higher during the day, the antisolar point descends below the horizon and is no longer visible, which is why anticrepuscular rays are confined to the twilight window around sunrise and sunset.
Can I photograph anticrepuscular rays with a smartphone?
Yes, especially on strong displays with high atmospheric particle loading. Modern smartphone wide-angle cameras capture the fan of rays competently. The main limitation is dynamic range: the tonal contrast between lit and shadowed bands benefits from shooting in RAW or ProRAW mode and processing in an app like Lightroom Mobile. The most important step is simply turning so that you face the antisolar point rather than the sunset. Your phone will handle the rest adequately on any strong display.
Do anticrepuscular rays appear at times other than sunrise and sunset?
Very occasionally they can form when the sun is only a few degrees above the horizon, within roughly the first or last fifteen minutes of daylight. Beyond that window the sun is too high, the antisolar point is below the horizon, and cloud shadows are too short to span the full sky. The phenomenon is overwhelmingly associated with the minutes immediately around sunrise and sunset, which is exactly when dedicated light chasers are already in position with cameras ready.
Start Looking Both Ways
If you want to talk through the locations, timing, and conditions for your first deliberate anticrepuscular ray shoot, or if you have a question about any of the optical phenomena covered on this site, head to the contact page and get in touch. Sharing what you have seen and what you are chasing next is how this community of light chasers keeps learning.