Rainbows have stood for nearly everything humans care about most: divine promises, cosmic danger, bridges between worlds, political solidarity, and hope in crisis. Few natural phenomena have accumulated as much symbolic weight across as many cultures, and remarkably, many of those meanings overlap even when the cultures that produced them had no contact with one another. The arc of light that appears when sunlight passes through water droplets has been interpreted as a serpent, a bow, a bridge, a flag, and a sign from the gods, sometimes all within a single tradition.
The Rainbow Serpent and Indigenous Traditions
Among the oldest and most persistent rainbow symbols on Earth is the Rainbow Serpent of Aboriginal Australia. Described as one of the most powerful and widespread Ancestral Beings in Aboriginal culture, the Rainbow Serpent pervades oral history, ceremony, performance, and visual art, and is associated with great acts of both creation and destruction.1Archaeology in Oceania. Birth of the Rainbow Serpent in Arnhem Land rock art and oral history Rock art depicting the serpent dates back thousands of years, making it one of the longest continuously held religious ideas anywhere in the world.
What makes the Rainbow Serpent especially interesting is that for a long time scholars assumed it was unique to Aboriginal Australia. Since A. R. Radcliffe-Brown first described the tradition in detail in 1926, the Rainbow Serpent culture complex was treated as the exclusive domain of Aboriginal peoples. These traditions typically represent the rainbow as an enormous spirit snake that guards springs and other water sources when it is not visible in the sky.2Anthropos. The Myth of the Rainbow Serpent “Myth” But serpent-rainbow associations turn up in traditions from West Africa, Southeast Asia, and parts of South America as well, which raises unresolved questions about whether the idea traveled with ancient human migrations or arose independently in response to the same visual stimulus: a shimmering arc that looks, if you squint, quite a lot like a snake draped across the sky.
In many Indigenous traditions worldwide, rainbows are not simply beautiful. They are dangerous, ambiguous, or at least commanding of respect. Some Amazonian groups traditionally warned children away from pointing at rainbows, and several West African traditions link the rainbow to a python spirit associated with water and fertility. The pattern is strikingly consistent: where the rainbow appears, water is being guarded, moved, or transformed, and the being responsible deserves caution as much as reverence.
Divine Bridges and Covenants
If Indigenous serpent traditions see the rainbow as a living creature in the sky, the major monotheistic and polytheistic religions of Eurasia more often see it as a sign placed there deliberately by a god. The most widely known example in the Western world is the covenant rainbow of the Hebrew Bible. In the Book of Genesis, after the floodwaters recede, God sets a rainbow in the clouds as a sign that the earth will never again be destroyed by a universal flood. The rainbow here is not a being; it is a message, a divine Post-It note meant to reassure both God and humanity that the worst is over.
Norse mythology took a different but equally vivid approach. Bifrost, the “trembling road,” was a burning rainbow bridge connecting Midgard (the human world) to Asgard (the realm of the gods). It was said to be extraordinarily strong but destined to shatter when the forces of chaos ride across it during Ragnarok, the end of the world. The rainbow here is infrastructure: literally the path between mortal and divine planes. In Hindu tradition, the rainbow is sometimes called Indra’s bow, the weapon of the king of the gods, linking it again to divine power. Ancient Greek sources connected the rainbow to the goddess Iris, a messenger who traveled between the gods and humanity along the arc of colors.
What all of these have in common is the idea that the rainbow connects two separate realms. Whether the connection is a covenant between God and humanity, a bridge between worlds, or a messenger’s path, the rainbow functions as a link between what is ordinary and what is numinous. That shared intuition probably has something to do with the rainbow’s physical behavior: it appears to touch both the earth and the sky, it cannot be approached or touched, and it vanishes when conditions change. It looks, in other words, exactly like the kind of thing a god might use to communicate.
Why the Physics Makes the Symbolism Work
Part of the reason rainbows have accumulated so much symbolic freight is that they behave in genuinely strange ways. You cannot walk up to a rainbow. It moves as you move. Two people standing side by side are technically seeing different rainbows, because the geometry depends on the angle between the observer, the sun, and the water droplets. And the colors, while apparently vivid, do not have sharp boundaries. All of this lends itself to metaphor.
The basic mechanism is refraction and reflection of sunlight inside water droplets. When light enters a raindrop, it slows down, bends, bounces off the back of the drop, and exits at a characteristic angle, around 42 degrees from the direction of the incoming light for the primary bow. Different wavelengths bend by slightly different amounts, which is why you see red on the outer edge and violet on the inner edge. But modern atmospheric optics has refined this picture considerably. Natural raindrops are not perfect spheres; they flatten as they fall, becoming slightly oblate, and the full explanation of what we see requires accounting for those non-spherical shapes and the range of drop sizes present in any real rain shower.3IOPscience (European Journal of Physics). Rainbows in nature: recent advances in observation and theory
The secondary rainbow, fainter and with colors reversed, results from light bouncing twice inside each droplet before escaping. Between the primary and secondary bows lies Alexander’s dark band, a region that appears noticeably darker than the sky around it because no light from single or double reflections reaches that angular range. Research into how the width of this dark band changes depending on the liquid involved has even been extended to model what rainbows might look like on Venus, where droplets would be sulfuric acid solution rather than water.4arXiv. Rainbow formation: from Descartes to Venus
Supernumerary Bows and the Uncanny Details
If you have ever looked closely at a bright rainbow, you may have noticed faint pink or green bands just inside the top of the primary arc. These are supernumerary bows, and they are caused by a different optical process than the main rainbow. Where the primary bow comes from refraction and reflection, supernumerary bows are produced by interference: two rays of light that enter a raindrop on either side of the “rainbow ray” (the path of minimum deviation) can exit in parallel and overlap, reinforcing or canceling each other depending on wavelength.5ScienceDirect (Physics Reports). The mathematical physics of rainbows and glories The result is a series of faint colored fringes, typically two to four of them, that appear just beneath the top of the primary bow.
Supernumerary bows rarely extend around the full visible arc, because they depend on a narrow range of droplet sizes. In a typical rain shower, drops of many sizes contribute to the rainbow, and the slightly different interference patterns they produce wash each other out except near the top of the bow, where geometry is most favorable. Lab experiments with laser illumination and precisely shaped drops have shown that even more exotic features appear when drops are slightly flattened: cusps from rays bouncing five times inside a drop can extend into Alexander’s dark band when the drop’s aspect ratio is near 1.08.6PubMed. Generalized rainbows and unfolded glories of oblate drops: organization for multiple internal reflections and extension of cusps into Alexander’s dark band
None of this detracts from the symbolism. If anything, it deepens it. The rainbow is not a simple, clean arc of color; it is a layered, fragile, geometrically specific phenomenon that depends on exact conditions to appear. That fragility is part of what makes it symbolically potent. A sign from the gods probably should be hard to pin down.
The Rainbow Flag and Modern Pride
The most globally recognized modern use of rainbow symbolism is the rainbow pride flag, designed by Gilbert Baker in 1978 for the San Francisco Gay Freedom Day Parade. Baker chose the rainbow deliberately: it represented diversity and inclusiveness, each color standing for a different aspect of community life. The original flag had eight stripes; the version most commonly seen today has six. Over the decades, variants have been introduced to emphasize the inclusion of trans people and people of color, but the core idea remains the same: the rainbow represents a spectrum of identities existing together.
The flag became such a powerful emblem that it now operates as visual shorthand worldwide. Businesses display it during Pride Month, governments fly it from public buildings, and it has become perhaps the single most widely recognized symbol of LGBTQ+ identity. Its success as a symbol owes something to the rainbow’s pre-existing cultural associations with hope, renewal, and the bridging of differences, but it also works because the visual is vivid and unmistakable. You do not need to read a label to know what it means.
When the Rainbow Shifted to Health Workers
Symbols are not static, and the rainbow flag’s meaning proved more flexible than many expected. During the early months of the COVID-19 pandemic in 2020, rainbow imagery appeared in windows across the United Kingdom and parts of Europe, but this time the message was not about LGBTQ+ pride. Children drew rainbows and posted them in windows as a sign of support for National Health Service workers. The rainbow, a long-standing emblem of the LGBT+ community, was temporarily repurposed to express solidarity with frontline healthcare staff, turning what had been a symbol of a marginalized group into a consensual symbol of hope centered on a state institution.7Angles. From LGBT+ Pride to NHS Praise
This semantic shift was not universally comfortable. Some LGBTQ+ advocates worried that the reappropriation diluted the flag’s political meaning, effectively borrowing a marginalized community’s symbol for a mainstream cause without acknowledging its origins. Others saw the overlap as proof of the rainbow’s universality: the same image could hold multiple meanings simultaneously without one canceling the other. The tension was never fully resolved, and it illustrates something important about rainbow symbolism in general. Because the rainbow carries so many pre-existing associations (hope, diversity, divine promise, connection between worlds), any group that adopts it inherits all of those connotations whether it intends to or not.
The COVID-era rainbow episode also showed how quickly symbolic meanings can shift and layer. Within a few months, the same image in a British window could be read as support for the NHS, as a Pride symbol, as a children’s craft project, or as a generic expression of optimism, all depending on who was looking and what they brought to it. Few other symbols have that kind of semantic flexibility.
Peace Flags, Political Movements, and Other Uses
The LGBTQ+ pride flag and the NHS rainbows are the most prominent recent examples, but rainbow symbolism has been drafted into service by many other movements. The rainbow peace flag, with its seven colored stripes and the word “PACE” (Italian for peace), predates the pride flag by several decades and was widely displayed during anti-war protests in Italy in the early 2000s. The International Co-operative Alliance has used a rainbow flag since the early twentieth century, representing the unity of diverse peoples in cooperative enterprise. Various indigenous rights movements have used rainbow imagery to symbolize cultural diversity and sovereignty.
In Buddhism, the “rainbow body” is a concept in Tibetan tradition referring to an advanced state of realization in which the practitioner’s physical form dissolves into light at the moment of death. In Irish folklore, the pot of gold at the end of the rainbow captures something real about the rainbow’s physics: you can never actually reach the end, because the rainbow moves with you. The pot of gold is, in effect, a folk recognition that the rainbow is always receding, always promising something just out of reach.
Political movements adopt the rainbow not just for its beauty but for its built-in metaphor of plurality. A rainbow is not one color; it is the full visible spectrum. Any movement that wants to signal inclusion of diverse elements finds the rainbow ready-made for the job. This is also why corporations have enthusiastically adopted rainbow imagery during Pride Month and other occasions, a practice that has generated its own backlash under the label “rainbow-washing,” in which critics argue that displaying rainbow colors without substantive policy commitments is performative rather than meaningful.
Climate Change and the Future of Rainbows
Here is something most people have not considered: climate change is altering how often and where rainbows appear. A 2022 study projected that by 2100, the global average number of “rainbow-days” (days on which at least one rainbow occurs) will increase by roughly 4 to 5 percent, with the greatest increase under the highest emission scenarios.8Global Environmental Change. Global rainbow distribution under current and future climates The change is not uniform. Around two-thirds to four-fifths of land areas are projected to gain rainbow-days, while roughly a fifth to a third will lose them. The gain hotspots are mainly in high-latitude and high-elevation regions, places like northern Canada, Scandinavia, and mountainous areas, while losses are concentrated in areas expected to become drier or shift from snow to rain.
The researchers framed this as an example of how climate change affects what they called “non-tangible environmental attributes,” meaning things that matter to human experience and well-being but are not typically included in climate impact assessments. We tend to measure climate change in terms of temperature, sea level, and crop yield. Nobody budgets for the loss of rainbows. But the study makes a reasonable point: the visual and aesthetic character of landscapes matters to the people who live in them, and those characteristics are changing alongside the more measurable ones.
There is an irony in the projection. The regions likely to gain the most rainbow-days tend to have smaller human populations, while some densely populated tropical regions may see fewer. In other words, the places where more people could see rainbows might actually get fewer of them. Whether this matters in any practical sense is debatable, but it adds a new dimension to what rainbows “stand for.” They may increasingly stand for a kind of environmental nostalgia: the memory of a sky that used to behave differently.
Why One Symbol Keeps Getting Reused
The persistence of rainbow symbolism across cultures and centuries raises a genuine question: why this particular phenomenon? Sunsets are beautiful and universal. Lightning is dramatic and widespread. Auroras are spectacular where they occur. Yet none of these has accumulated the sheer density of symbolic meaning that the rainbow has.
A few qualities set the rainbow apart. It requires specific conditions (rain and sun simultaneously), so it is relatively rare compared to, say, a clear sky. It is temporary, lasting minutes rather than hours. It appears to span the entire sky, connecting earth and sky in a way that invites interpretation. It is made of distinct colors arranged in a fixed order, which reads visually as structure and meaning rather than randomness. And it cannot be approached, touched, or owned, which gives it an inherent quality of transcendence.
All of these features make the rainbow a natural container for ideas about hope (it appears after rain), diversity (it contains many colors), connection (it spans two points), promise (it is temporary and therefore precious), and the divine (it is untouchable and seemingly placed there for observers). No culture had to work hard to make the rainbow into a symbol. The rainbow does most of the symbolic work itself, which is probably why so many unconnected cultures arrived at overlapping interpretations independently. The Aboriginal Rainbow Serpent, the Norse Bifrost, the Biblical covenant, and the pride flag are all, in different vocabularies, saying something similar: this arc of color means that separate things are connected, and that connection matters.
What changes over time is not whether the rainbow is symbolic but who gets to control what it symbolizes. The COVID-era tension between pride and NHS meanings, the rainbow-washing debate, and the competition between peace flags and pride flags all reflect the same underlying dynamic. A symbol this powerful and this universally legible is always being contested. The rainbow does not belong to any one group or tradition, which is both its greatest strength as a symbol and the source of its recurring political friction.