Rainbows have long captured human imagination appearing as luminous, multicolored arcs across the sky after a storm, they are often associated with beauty, mystery, and even folklore about hidden treasures. But while they seem magical, rainbows are the result of precise physical processes involving light, water, and the observer’s perspective.
At its core, a rainbow is created when sunlight interacts with raindrops suspended in the air. When sunlight enters a water droplet, it slows down and bends, a phenomenon called refraction. This bending of light is what starts the separation of white sunlight into its constituent colors. Each color has a slightly different wavelength, so red, orange, yellow, green, blue, indigo, and violet bend at slightly different angles inside the droplet.
After refraction, the light reflects off the inner surface of the droplet. This internal reflection redirects the light back toward the observer. As it exits the droplet, the light bends again (another refraction), further spreading the colors into the vivid spectrum we see. Essentially, each raindrop acts like a tiny prism, and a full rainbow is formed by the collective effect of millions of these droplets.
Interestingly, the rainbow you see depends on your perspective. The sun needs to be behind you, and the rain must fall in front. The angle at which sunlight exits the droplets is usually about 42 degrees relative to the direction opposite the sun for the primary rainbow, which is why you see a semi-circular arc. In rare conditions, you may even spot a secondary rainbow, which is fainter and appears outside the primary rainbow with reversed colors, caused by two internal reflections of sunlight inside the droplets.
Beyond the science, rainbows have inspired myths, legends, and art across cultures. From Norse tales of bridges to gods to stories of pots of gold at their ends, rainbows have symbolized hope, beauty, and the connection between earth and sky.
In truth, while rainbows are a marvel of physics, they are also a reminder of nature’s artistry a fleeting, colorful spectacle that appears when sunlight meets water just right, offering a glimpse of the wonder that surrounds us every day.