80+ Atmospheric Optical Phenomena For Fantasy Worldbuilding54 min read

Auroras, halos, ghost lights, and rainbows! Welcome back, Outlander, to the 11th entry in Mythic Ecology, my series on how learning real-world landscape features can enrich our fantasy worldbuilding and storytelling. In this post I return to my minimalist framework for Dungeon Masters, Game Masters, fiction writers, and similar worldbuilders to merge the realms of general myth and geomorphology. Last entry I took a detour with 16 D&D Openers Beyond Taverns. As I resume my journey sketching a framework for designing Yridia, my unique D&D 5e fantasy world, let’s learn some atmospheric optical phenomena, with a visual guide!

All the images herein I use for educational and entertainment purposes, I claim no rights to any of them. For corrections or content removal requests, hit my contact page.

Let’s revisit my minimalist framework for my worldbuilding. The six archetype tags with which I will flag all the various real-world land features in my Mythic Ecology Series:

1. Settlements: habitable regions of either Work or Play, Familiar or Exotic, offering diverse narrative functions: a Day in the Life, Home Base, Personal Reasons, Gathering Supplies. Can subvert tropes with Ruins or Escape.
2. Omens: sensational, temporal, or particularly pointed features that offer narrative functions of forshadowing, and good or evil portents. Can subvert tropes with a Wild Goose Chase.
3. Overlooks: sites of magnitude and grandeur, living monuments which can function narratively for finding resolve, invoking spirits, or as a Call to Adventure. Can subvert tropes with Dread or Betrayal.
4. Passageways: transitional journeylands, including magical portals, functioning narratively for initiation and return, thresholds and tests, shortcuts and setbacks.
5. Abyss: a void or confined space presenting scarcity or temptation, desperation and danger. Can subvert tropes with a Timely Rescue or Secret Refuge.
6. Battlegrounds: sites fit for epic, sprawling encounters and climax conflicts. Can subvert tropes with Alternative Solutions.

Feel free to submit your own ideas, or draw outside the lines. Alright, let’s see how these atmospheric optical phenomena fit in with my framework.

TIP: Since most of this entry’s phenomena function as omens, if you want some prophecies to go along with them, I use the free D&D random prophecy generator tools from Fantasy Name Generators, Chaotic Shiny, and Springhole.

D&D 5e School of Magic Affinities – Abjuration, Conjuration, Enchantment, Illusion.

Aurora / Polar Lights – a natural skyborne light display, predominantly in high-latitude regions. Produced when solar wind disturbs the magnetosphere, ionizing and exciting atmospheric constituents, which emits light of varying color and complexity. Folklore associates it with evil fires, the campfires of dead spirits, sulfuric cures, fluorescent glaciers, seas of flame, and pleasant afterlife.
[Omens, Overlooks, Abyss]

Picket Fence Aurora – an elongated, localized aurora pattern with green and purple hues, below the primary auroral band, 10 to 20 degrees equatorward, extending in a relatively narrow arc for hundreds of miles east to west. Typically quite faint.
[Settlements, Omens]

Coronae form from diffraction in comparatively large ice crystals.

D&D 5e School of Magic Affinities – Abjuration, Conjuration, Divination, Illusion.

Lunar Diffraction Ring / Corona – produced by the diffraction of moonlight by individual small water droplets and sometimes tiny ice crystals of a cloud. Smaller droplets produce a larger corona, more visible with more uniform droplets. Its full form consists of several concentric, pastel-colored rings around the celestial object and a central bright area called aureole (often the only visible part, a bluish-white disk fading to reddish-brown toward the edge).
[Omens, Overlooks]

Solar Diffraction Ring / Corona – produced by the diffraction of sunlight by individual small water droplets and sometimes tiny ice crystals of a cloud. Smaller droplets produce a larger corona, more visible with more uniform droplets. Its full form consists of several concentric, pastel-colored rings around the celestial object and a central bright area called aureole (often the only visible part, a bluish-white disk fading to reddish-brown toward the edge).
[Omens, Overlooks]

Pollen Corona – a small and vertically-elongated corona, sometimes with bright spots on rings. Produced by sunlight or moonlight diffracting through pollen in the air.
[Omens, Passageways]

Atmospheric ghost lights refer to various unexplained light phenomena of a purported supernatural nature, with rich real-world folklore. Naturalistic explanations include: the bioluminescence of various animals, geophysical lights like piezoelectrics or marsh gas and spontaneous combustion of phosphorous or methane, starlight reflections, electrical activity, undersea volcanic fires, mirages, fishing boat lights, ball lightning, and optical illusions associated with these.

D&D 5e School of Magic Affinities – Conjuration, Divination, Enchantment, Evocation, Illusion, Necromancy, Transmutation.

Kitsunebi – a flickering line of mysterious red, orange, or blue fires numbering ten to hundreds. Reported in hot summers, cloudy times, and with changing weather, on remote hillsides. Folklore associates this with foxes starting fires using human and horse bones, “fox torches” and fungal fires on trees.
[Omens, Passageways]

Min Min Light / Abu Fanoos – fuzzy, disc-shaped lights appearing to hover just above the horizon, described as white or changing color from white to red to green and back. Described as sometimes dim and other times bright enough to cast shadows. Witnesses describe the light as appearing to approach and retreat observers, or to keep pace with them, sometimes disappearing when fired upon, only to reappear later. Folklore implies chasing them becomes fatal.
[Omens, Overlooks, Abyss, Battlegrounds]

Onibi – a collection of atmospheric ghost lights supposed to occur in natural spaces, primarily blue luminescent orbs, sometimes also bluish white, red, and yellow. Size ranges from candle flame to the size of a human, or larger. One or two, up to twenty or thirty, can appear at once. Often appear on rainy days. Folklore depicts them as the spirits of human and animal corpses, often resentful ones.
[Omens, Battlegrounds]

Shiranui – an atmospheric ghost light that take place over open waters near the shore between midnight and dawn, in weak winds, near the Full Moon. Purportedly, one or two flames appear then split and multiply into several hundred or thousand flames in a row, spanning miles, moving farther away as one approaches. Forms include a large fireball rising from the sea’s surface up to 60 feet, and a line of pale red fiery globes drifting along the tide. Folklore depicts them as lamps of the Dragon God.
[Settlements, Omens, Passageways, Abyss, Battlegrounds]

St. Elmo’s Fire – when sharp or pointed objects under a strong atmospheric electric field produce a coronal discharge of luminous plasma, a bright blue or violet glow, sometimes flame-like, often with a hissing or buzzing sound. Caused by the ionization of air in low-light conditions. Sometimes appears on ships at sea during thunderstorms as glowing balls of light. Folklore suggests this is a good omen, the presence of a patron saint, but more rarely a bad omen of divine judgment.
[Omens, Overlooks]

Tenka – a supposed nighttime illumination while traveling, or mysterious flying fires that make great noise in the evening sky in the summer. Roughly the size of a paper lantern, and depicted as lumps of fire falling from the sky. Folklore suggests they improve weather but curse individual households with sickness, or a premonition of a conflagration, or a vengeful spirit.
[Omens, Passageways, Abyss]

Will-o’-wisp / Fool’s Fire / Spook-Light / Ghost-Light / Fairy Fire – a purported marsh gas apparition resembling a flickering lamp or lantern. Seen especially by wetland travelers at night. Includes many regional variations, such as St. Louis Light, Marfa Lights, Naga Fireballs, and Hessdalen Light, among many. Folklore associates this with ghosts, fairies, and elemental spirits. Metaphorically suggests an elusive or delusive hope or goal, or something sinister and confounding.
[Settlements, Omens, Passageways, Abyss]

D&D 5e School of Magic Affinities – Abjuration, Conjuration, Divination, Illusion, Necromancy, Transmutation.

Glory – one or more concentric, successively dimmer rings around the shadow of the observer’s head, each red on the outside and bluish towards the center. Caused by sunlight or moonlight refracting inside tiny water droplets in mist or clouds. Sometimes mistaken for the larger full-circle rainbow. Folklore associates these with the head halos of iconic saints.
[Omens, Overlooks, Passageways, Abyss]

Brocken Spectre / Brocken Bow / Mountain Spectre / Anticorona – a magnified and enormous-appearing shadow of an observer projected upon clouds opposite the Sun’s direction. The figure’s head often has a glory of halo-like rings of colored light, appearing opposite the Sun’s direction when uniform water droplets in clouds refract and backscatter sunlight. Can appear on misty mountainsides or cloud banks. Folklore includes causing a thirsting sickness, haunted self-pursuit, and inspiring mass confidence.
[Omens, Overlooks, Passageways, Abyss]

Hotspot / Heiligenschein – when a bright spot appears around the shadow of the viewer’s head in the presence of dew. Spherical dew droplets act as lenses that focus light onto surfaces behind them; when the light scatters and reflects off that surface, the lens re-focuses it back into the direction it came from. Similar to glory, but different mechanism.
[Omens, Overlooks, Passageways]

D&D 5e School of Magic Affinities – Abjuration, Divination, Evocation, Illusion.

Afterglow – a broad arch of whitish or pinkish sunlight in the sky scattered by fine particulates like atmospheric dust. May appear above the highest clouds in fading twilight, or reflected off high snowfields in mountain regions long after sunset. The particles scatter upon white light.
[Omens]

Airglow / Nightglow – a faint emission of light by a planetary atmosphere. Causes the night sky to never be completely dark, even without starlight and diffused sunlight.
[Omens]

Alpenglow – a horizontal reddish glow long after sunset or long before sunrise, near the horizon opposite the Sun, where the solar disk is just below the horizon. Visible as illuminated mountains, or clouds lit through backscatter. Forms with the backscattering of red sunlight by aerosols and fine dust particles low in the atmosphere.
[Omens, Overlooks, Passageways]

Blue Hour – the 20-minute-or-so period of morning or evening twilight, during the civil and nautical stages, when the Sun is at a significant depth below the horizon and residual, so indirect sunlight takes on a predominantly blue shade. With a clear sky this can include yellow, orange, red, and blue, as shorter wavelengths of visible light diffuse differently than the longer wavelength reds.
[Omens]

Belt of Venus / Venus’s Girdle / Antitwilight Arch – visible shortly before sunrise or after sunset, during civil twilight, when a pinkish glow extending roughly 10-20* above the horizon surrounds the observer. Created by backscatter of reddened sunlight, like with alpenglow.
[Omens]

False Sunrise – when the Sun appears to have risen, but is actually still some distance below the horizon. Happens through various diversions of sunlight: sunlight reflected off the bottom of clouds, a polar mirage from the Novaya Zemlya Effect, or an ice crystal halo like an upper tangent arc or sun pillar.
[Omens]

False Sunset – where the Sun appears as setting or to have set while actually still above the horizon, or where the Sun has already set below the horizon, but still appears on or above it. Can give the impression of an actual sunset. Causes can include sunlight reflected off the bottom of clouds, a polar mirage from the Novaya Zemlya Effect, or reflection and refraction of sunlight by small ice crystals (often in cirrostratus clouds), caused by phenomena like tangent arcs, sun pillars, and subsun.
[Omens]

Golden Hour – the period of daytime shortly after sunrise or before sunset, during which daylight appears redder and softer than when the Sun rests higher in the sky.
[Omens, Overlooks]

Haze – when dry particulates obscure the clarity of the sky, including fog, ice fog, steam fog, mist, haze, smoke, volcanic ash, dust, sand, and snow.
[Omens, Abyss]

Steve – a purple and green light ribbon in the sky, generated in the ionosphere. Not an aurora, but frequently appears alongside picket fence auroras.
[Omens, Overlooks]

D&D 5e School of Magic Affinities – Abjuration, Conjuration, Divination, Enchantment, Evocation, Illusion, Transmutation.

Halo – produced by sunlight interacting with ice crystals suspended in the atmosphere, which act as prisms and mirrors. Can have many forms, ranging from colored or white rings, to arcs and spots in the sky. May occur near the Sun or Moon, sometimes elsewhere, or even the opposite part of the sky.
[Omens, Overlooks]

22* Halo / Moon Ring / Winter Halo / Circular Halo – an optical ring with an approximate 22* radius around the Sun or Moon. When visible around the moon, it is called a moon ring or winter halo. Large and visible up to 100 days per year. Folklore indicates a warning of approaching storms, and a supernatural prison for a murderous king.
[Omens, Overlooks, Abyss]

Circumscribed Halo – an oval ring circumscribing a circular 22* halo centered on the sun or moon; as the sun rises above 70* it essentially covers the 22* halo. Slightly reddish on the inner edge, facing the sun or moon, and bluish on the outer edge. The points directly below and above the sun or moon lie tangential to the 22* halo, however the sides can form distinct, downward-drooping lobes, but approaching circular as elevation increases.
[Omens, Overlooks]

Circumhorizontal Arc / Circumhorizon Arc / Lower Symmetric 22* Plate Arc / Fire Rainbow – formed by the refraction of sun- or moonlight in plate-shaped ice crystals suspended in the atmosphere, typically in cirrus or cirrostratus clouds. Sometimes seen only as fragments. In its full form, the arc appears as a large, brightly spectrum-colored band parallel to the horizon, located far below the Sun or Moon, twice the 22* halo. In folklore, sometimes interpreted as a bridge to the realm of the gods.
[Settlements, Omens, Overlooks, Passageways]

Circumzenithal Arc / Circumzenith Arc / Upside-Down Rainbow / Bravais Arc – an ice halo similar to a rainbow, generally in cirrus or cirrostratus clouds, rather than from raindrops. Roughly 46* above the sun, typically a quarter of a circle centered on the zenith. One of the most vivid halos, with purer violets and reds than a rainbow.
[Omens]

Light Pillar / Sun Pillar / Solar Pillar – a vertical beam of light appearing to extend above or below a light source, in this case, the Sun. Created by the reflection of light from tiny atmospheric ice crystals and high-altitude clouds; as the crystals fall they naturally orient themselves horizontally, but as they wobble, their deviation stretches the reflection into a vertical column.
[Omens, Overlooks, Passageways]

Parhelic Circle – a horizontal white line on the same altitude as the Sun, or occasionally the Moon, potentially stretching around the sky, but more often sectional. Can show a bluish or greenish tone near the 120* parhelia and be reddish or deep violet along the fringes. Forms as vertical hexagonal ice crystals reflect beams of sunlight, either without light passing through, or one or more reflections inside the crystal.
[Omens]

Subsun – a glowing spot visible within clouds or haze when observed from above, appearing directly below the sun as its light reflects off of numerous, tiny, mirror-like ice crystals shaped like flat hexagonal plates in the atmosphere. This creates a virtual image of the sun appearing below the horizon, similar to sunlight reflecting onto a body of water.
[Omens, Overlooks]

Sun Dog / Sundog / Mock Sun / Parhelion – a subtly-colored bright spot on one or two sides of the Sun, at the same altitude as the Sun. Red-colored nearest the Sun, progressing to oranges and blues before merging into white. Formed by the prismatic action of ice crystals. Two Sun Dogs often flank the Sun within a 22* halo. Folklore includes a sign of good luck in battle, two wolves hunting the Sun and the Moon, a portent of blizzards, and the approach of deific vengeance against traitorous and heavy-handed rulers.
[Omens, Overlooks, Passageways, Abyss, Battlegrounds]

Moon Dog / Moondog / Mock Moon / Paraselene – a circular bright spot on a lunar halo caused by the refraction of moonlight by hexagonal-plate-shaped ice crystals in cirrus or cirrostratus clouds. Part of a 22* halo, roughly 10 Moon diameters outside the Moon. Analogous to Sun Dogs, but rarer because of Moon brightness, and less colorful.
[Omens, Overlooks, Passageways, Abyss, Battlegrounds]

Tangent Arcs – appear above and below the Sun or Moon, tangent to a 22* halo, red toward the Sun and blue away from it. They form when rod-shaped hexagonal ice crystals have their long axis aligned horizontally. Both upper and lower tangent arcs exist, and vary with sun elevation. With low elevation, uppers appear as arcs over the sun with a sharp angle, but as the sun rises, the curved wings lower toward the 22* halo and elongate, eventually uniting with the lower tangent arc to form a circumscribed halo. The lower arc appears more rarely. As the sun slips over the horizon, the lower tangent arc forms a sharp, wing-shaped angle below the sun, and as it rises the arc first folds upon itself and then widens, eventually merging with the upper. Requires an elevated observation point, such as a mountain.
[Omens, Passageways]

D&D 5e School of Magic Affinities – Abjuration, Conjuration, Divination, Enchantment, Evocation, Illusion, Transmutation.

120* Parhelion – white-bluish bright spots on the white parhelic circle, produced by at least two interior reflections in hexagonal ice crystals. Difficult to observe, and occasionally appear alongside sun dogs.
[Omens]

46* Halo – a large ring centered on the Sun at roughly twice the distance as the much more common 22* halo, larger and fainter than the latter, with the outer edge more diffuse. Often confused with supralateral and infralateral arcs.
[Omens, Overlooks, Passageways, Battlegrounds]

Anthelion – a rare, faint white spot opposite to the sun on top of a parhelic circle, sometimes crossed by an X-shaped pair of diffuse arcs.
[Omens, Passageways]

Bishop’s Ring – a diffuse brown or bluish halo observed around the sun, typically after large volcanic eruptions.
[Omens, Abyss]

Elliptical Halo – a rare halo, solar or lunar. Smaller than 22* halos, and visible with a shielded light source. Cause debatable. Can also come in the short-lived form of a Bottlinger’s ring.
[Omens, Overlooks]

Infralateral Arc / Lower Lateral Tangent Arc – appears similar to a rainbow under a white parherlic circle. Located outside the rare 46* halo, but located below the parhelic circle, in contrast to a supralateral arcs. Between sunrise and the Sun reaching 50* over the horizon, the 46* halo has two infralateral arcs on either side, their convex apexes tangent to it. With the Sun above 68*, the two arcs unite to a single concave arc tangent to the 46* halo vertically under the sun. Caused by light entering horizontally oriented, rod-shaped hexagonal ice crystals and exiting through a prism side. Occurs roughly once a year, observed with circumscribed halos and upper tangent arcs.
[Omens]

Kern Arc – a complete and faint circle around the zenith, in contrast to the circumzenithal arc. Formed by rays entering the top faces of horizontal plate crystals and leaving through a near vertical side face, producing an internal reflection off a side face inclined at 60* to the exit face. Extremely rare, as it requires triangular hexagonal crystals with three alternate side faces much shorter than the others.
[Omens]

Lowitz Arc – a rare ice crystal halo which forms a luminous arc extending inward from a sun dog, potentially extending above or below the sun. Caused by sunlight refracting through ice crystals.
[Omens, Overlooks, Passageways]

Parry Arc – a rare halo appearing over a 22* halo together with an upper tangent arc. The result of light passing through two side faces forming a 60* angle, generated by double-oriented hexagonal column crystals, where both the central main axis of the prism and the top and bottom prism side faces orient horizontally. Includes upper and lower arcs, in either sunvex or suncave orientations.
[Omens, Overlooks, Passageways, Battlegrounds]

Subhelic Arc – a rare halo curving upward from the horizon and touching an arc above the point directly opposite the Sun from the observer. Formed by internal reflections through ice crystals acting as prisms.
[Omens, Overlooks, Passageways, Battlegrounds]

Subparhelic Circle – a rare halo below the horizon; the subhorizon counterpart to the parhelic circle. It passes through both the subsun below the sun and the antisolar point opposite the sun. Coexists with other rare optical phenomena.
[Omens, Passageways]

Supralateral Arc – a large, faintly rainbow-colored band in a wide arc above the Sun and appearing to encircle it, about twice the distance of a 22* halo. In reality it never forms a circle and never reaches below the Sun. Has a red side toward the Sun and a blue part away from it. Touches a circumzenithal arc from below.
[Omens]

Cloud Iridescence / Irisation – a colorful optical phenomenon, pastel or vivid, in a cloud in general proximity to the Sun or Moon. Primarily happens in altocumulus, cirrocumulus, lenticular, and cirrus clouds, and rarely polar stratospheric clouds. Produced by diffraction in small water droplets or ice crystals individually scattering light; larger crystals produce halos instead of iridescence.
[Omens, Overlooks, Passageways]

D&D 5e School of Magic Affinities – Abjuration, Conjuration, Divination, Enchantment, Illusion, Transmutation.

Crown Flash / Leaping Sundog – the brightening of a thunderhead crown followed by the appearance of aurora-like emanations into the clear atmosphere. Can appear as tall streamers, pillars of light, or a massive searchlight flash. Rare and visible only from specific positions.
[Omens, Overlooks, Passageways]

Iridescent Mountain Clouds – when mountains induce cloud formation as moist air forces upwards and cools then condenses, forming banner clouds. This creates uniform droplets, allowing for intense iridescence from diffraction.
[Omens]

Noctilucent Cloud / Night Shining Clouds – a tenuous cloud-like phenomenon in the upper atmosphere, consisting of ice crystals, and only visible during astronomical twilight. Most often observed during summer, with the Sun below the observer’s horizon but while the clouds still have sunlight, in latitudes between 50* and 70* north and south of the Equator.
[Omens]

Polar Stratospheric Clouds / Nacreous Clouds – iridescent clouds in the winter polar stratosphere at extreme altitudes (~9-15 miles up). Found during civil twilight, in winter, or in northerly latitudes. Arises from ozone depletion, or frozen ice crystals.
[Omens]

D&D 5e School of Magic Affinities – Conjuration, Enchantment, Illusion, Transmutation.

Green Flashes / Green Rays – distinct green spots briefly visible above the upper rim of the Sun’s disk, lasting no more than a second or two. More rarely, a green ray shooting up from the sunset or sunrise point. Occur just after sunset or right before sunrise, more often stable, clear air. Includes inferior-mirage flash, mock-mirage flash, sub-duct flash, and green ray forms. Very rarely a blue flash can occur.
[Omens, Passageways]

Inferior Mirage – a mirage located under the real object, typically appearing as blue sky appearing upside-down on the ground in an unstable projections, like an illusory desert oasis, or over lakes or sea. Caused by atmospheric temperature gradients where cold air over warm air causes light to refract upward. Mixing of hotter and cooler air layers leads to turbulence, distorting the image, making it vibrate, tower, or stoop. Includes heat shimmer.
[Settlements, Omens, Passageways, Abyss, Battlegrounds]

Superior Mirage – a mirage with the light rays bent down, so the image appears above the true object, right-side up or upside-down, or a mixture. Occurs with air below the line of sight colder than air above it, a temperature inversion. Less common than inferior mirages, but more stable. Common in polar regions, especially over large ice sheets. Less smooth and stable at more moderate latitudes.
[Settlements, Omens, Passageways, Abyss, Battlegrounds]

Fata Morgana – a complex form of superior mirage seen in a narrow band right above the horizon, significantly distorting a base objects and often turning them unrecognizable, sometimes also changing rapidly. Includes several inverted and upright images stacked on top of one another, with alternating compressed and stretched zones. Occurs when rays of light bend as they pass through air layers of contrasting temperatures in a steep thermal inversion, which forms an atmospheric duct that can become a refracting lens. Viewable on land, sea, polar regions, or deserts. Named after the Arthurian sorceress Morgan le Fay, with folklore of fairy castles in the air or false land created by witchcraft to lure sailors to their deaths.
[Settlements, Overlooks, Omens, Passageways, Abyss, Battlegrounds]

Rainbow / Solar Rainbow – a multicolored circular arc in the sky. Caused by reflection, refraction, and dispersion of light in water droplets resulting in a spectrum of light appearing in the sky. When caused by sunlight, they appear in the section of sky opposite the Sun. They come in many forms. Primary rainbows have red outer bands and violet inner bands.
[Omens, Overlooks, Passageways, Abyss]

D&D 5e School of Magic Affinities – Abjuration, Conjuration, Divination, Illusion, Transmutation.

Alexander’s Band – the unlit sky between with two concentric rainbows. The primary bow has a minimum deviation angle of 137.5*. Light can deviate right back to the observer, or brighten the inside of the rainbow. The secondary bow is about 230*, an inside-out version of the primary, with the colors reversed, potentially brightening outside the bow.
[Omens, Passageways, Abyss]

Dewbow – similar to a rainbow, but where dewdrops instead of rain droplets reflect and disperse sunlight. Forms outdoors in early morning after a clear night, most easily on surfaces isolated from ground heat, such as grass, leaves, and spiderwebs; seen most in Autumn.
[Settlements, Omens]

Double Rainbow – a rainbow with a second arc outside the primary arc, with the color order reversed: red on the inner side. Caused by light reflecting twice inside the droplet before leaving.
[Omens, Overlooks, Passageways]

Triple Rainbow – extremely rare versions of double or twinned rainbows, with a tertiary arc.
[Omens, Overlooks, Passageways]

Fogbow / White Rainbow / Sea-Dog – similar to a rainbow, but where fog instead of rain droplets reflect and disperse sunlight. Has faint colors because of small water droplets, with a red outer edge and bluish inner edge, but can also appear white, or have multiple, more vivid inner rings. Can also happen at sea. Called a cloudbow when seen in clouds.
[Omens, Passageways]

Full-Circle Rainbow – sometimes visible from elevation, requiring both the presence of water droplets below the observer’s horizon, and unobstructed sunlight. Can have secondary bows or supernumerary bows as well, and can be produced artificially by spraying a water mist while facing away from the Sun. Can occur alongside glory and fogbow as well. Different from 22* halo.
[Omens, Overlooks, Passageways]

Monochrome Rainbow / Red Rainbow – formed like a normal rainbow but during sunrise or sunset, the Sun’s low angle can cause shorter wavelengths of light to scatter, leaving only reds.
[Omens, Passageways, Abyss]

Moonbow / Lunar Rainbow / White Rainbow – a rainbow produced by moonlight rather than direct sunlight. Caused by the refraction of light in water droplets, such as a rain shower or a waterfall, positioned in the opposite part of the sky from the moon relative to the observer. Fainter than solar rainbows. Associated with Full Moons.
[Omens, Overlooks, Passageways]

Reflected Rainbow & Reflection Rainbow – when two complementary mirror bows appear above and below the horizon via reflection over a body of water, with different light path origins. Reflected Rainbows, more easily visible, appear in the water surface below the horizon, first deflected by the raindrops then reflected by the water body. Reflection Rainbows, more rarely visible, require sunlight reflecting off a still water body before reaching the raindrops, intersecting a normal rainbow at the horizon then appearing above it. This can theoretically manifest as eight distinct simultaneous rainbows: a primary and secondary bow above the horizon, their reflected counterparts below it, the reflection primary and secondary bows above it, and their reflected counterparts below it.
[Omens, Overlooks, Passageways]

Supernumerary Rainbow / Supernumerary Bands / Stacker Rainbow – when one or several narrow, faintly colored bands border the violet edge of a rainbow, inside the primary bow, or, more rarely, outside the secondary. They have subdued pastel hues, mainly pink, purple, and green, successively fainter along with their distance. Requires very tiny and uniform water droplets, which produce sequences of constructive and destructive interference between rays of light within raindrops, in contrast to normal rainbows. Associated with fogbows.
[Omens, Overlooks, Passageways]

Twinned Rainbow – when two rainbow arcs split from a single base, appearing in the same order and color profile as the primary bow. Sometimes has a normal secondary rainbow. Caused by combinations of rain showers with different-sized raindrops. Similar to supernumerary bands, but with different color profiles.
[Omens, Passageways]

D&D 5e School of Magic Affinities – Divination, Evocation, Illusion, Necromancy.

Anticrepuscular Rays / Antisolar Rays – similar to crepuscular rays, but appear opposite of the Sun in the sky. Nearly parallel, they converge toward the antisolar point due to linear perspective. Most frequently visible around sunrise or sunset. Sometimes enclosed by a rainbow.
[Settlements, Overlooks, Omens, Battlegrounds]

Crepuscular Rays / Sunbeams / Sun Rays / Splintered Light / God Rays – rays of sunlight appearing to radiate from the Sun. Shining through openings in clouds (particularly stratocumulus) or other objects, darker cloud-shadowed volumes separate these columns of sunlit particulates. Actually near-parallel shafts of sunlight, a perspective effects gives the semblance of convergence.
[Omens, Overlooks, Passageways, Battlegrounds]

Cloud Shadow – when a cloud casts its shadow across the sky. An inverse of crepuscular ray.
[Omens, Abyss]

Downward Mountain Shadow – when an observer at a summit perceives a mountain casting an apparent triangular shadow onto the sky. Caused by a perspective effect, as the Sun causes the fully-shaded parts of the shadow to converge and taper away due to the different ratio of lengths between Sun, Earth, and mountain.
[Omens, Overlooks, Passageways, Abyss]

Corrugated Mountain Shadow – when a downward mountain shadow produces 2D ridge shadow effects on an opposite valley wall as well as 3D shadows cast into the air itself by the pinnacle, creating an apparent shadow superimposition.
[Omens, Overlooks, Passageways, Abyss]

Upward Mountain Shadow – when a mountain shadow projects upward onto a lower level translucent cloud or mist, with the shadow or outline appearing above the actual mountain peak.
[Omens, Overlooks, Passageways, Abyss]

Earth’s Shadow / Earth Shadow – the shadow that Earth itself casts onto its atmosphere and into outer space, toward the antisolar point. During twilight, the shadow’s visible fringe appears in a clear sky as a dark and diffused band low above the horizon.
[Omens]

D&D 5e School of Magic Affinities – Abjuration, Conjuration, Illusion.

Iceblink – a white light seen near the horizon, especially on the underside of low clouds. Results from reflection of sunlight off an icefield. Related to water sky.
[Omens, Passageways]

Water Sky – dark spots that appear underneath low-lying clouds in regions with large areas of sea near water, mostly polar latitudes, as light reflects upward. These clouds can indicate the presence of the sea and the general direction of water without direct view of the water beyond the ice. Related to iceblink.
[Omens, Passageways]

Moonglade / Moon Glitter / Yakamoz – the bright reflection of the moon’s light on an expanse of water.
[Omens, Overlooks, Passageways]

Sun Glitter / Sun-Glade – bright, sparkling light on a body of water as sunlight reflects from water waves. Created by ripples, which create many small images of the Sun. The lower the sun, the longer and redder the glitter. With the Sun low over the horizon, the waves can obstruct the reflection with a shadow over the glitter.
[Omens, Overlooks, Passageways]

D&D 5e School of Magic Affinities – Abjuration, Divination, Illusion, Necromancy.

Countershine / Gegenschein – a faintly bright spot in the night sky, around the antisolar point, caused by the backscatter of sunlight by interplanetary dust.
[Omens, Abyss]

Zodiacal Light / False Dawn – a faint, diffuse, roughly triangular white glow visible in the night sky and appearing to extend from the Sun’s direction and along the zodiac, straddling the ecliptic. Caused by interplanetary dust scattering sunlight. Best seen during twilight after sunset in spring and before sunrise in autumn, with the zodiac at a steep angle to the horizon. Contributes to the overall natural light in a clear and moonless night sky.
[Omens, Overlooks, Abyss]

I hope you enjoyed this eleventh entry in my Mythic Ecology series! I look forward to continuing with it, I have some greater ambitions for developing this series into worldbuilding web tools. Give this a share if you liked it, and let me know in the comments if you have any feedback. I publish new posts on alternating Tuesdays. In the meantime, I post original D&D memes and writing updates over on my site’s Facebook Page. Also, if you want to keep up-to-date on all my posts, check out my Newsletter Sign-Up to receive email notifications when I release new posts. A big thanks as always to my Patrons on Patreon, helping keep this project going: Adam, Alexander, Anthony, Chris, Eric & Jones, Geoff, Jason, Rudy, and Tom. Thanks for your support!