Rainbows on Schedule: Niagara’s Daily Magic
🌈 Rainbows on Schedule: Niagara’s Daily Magic 🌈
At Niagara Falls, some wonders are so reliable they feel like clockwork. On sunny days, certain rainbows appear in the same spots almost every day—so consistent that our guides at Go Niagara Tours can point to the mist and say, “Wait for it… there it is.”
It’s not luck. It’s physics.
When sunlight hits the sheets of mist rising from the Falls, the water droplets act as millions of tiny prisms. They bend and reflect the light at just the right angles, splitting it into the spectrum we see as a rainbow. Because the Falls’ mist patterns and the sun’s position are relatively constant at certain times of day, the effect is predictable.
🎤 Our guides love explaining:
Why rainbows are always arcs at a 42° angle from the light source.
How double rainbows form (yes, you can see millions here).
Why the colors appear in reverse order on the second arc.
📐 Why are rainbows always at 42°?
When light refracts and reflects inside a droplet, there’s a specific angle where the outgoing light is most concentrated.
For the wavelengths we see as red, this “brightest return” happens at about 42° from the line opposite the sun (the antisolar point).
Violet bends more sharply, so its angle is around 40°, which is why it ends up on the inside of the primary rainbow.
This angle doesn’t change no matter where you are. That’s why you can never “walk up to” a rainbow—it’s always at that 42° cone relative to your eyes.
🌈 Why are the colors reversed in a double rainbow?
A single (primary) rainbow happens when light enters a raindrop, bends (refracts), reflects once inside the drop, and then exits.
A secondary rainbow forms when the light reflects twice inside the droplet before exiting.
That second internal reflection flips the order of the colors. In the primary rainbow, red is on the outside and violet on the inside. In the secondary, it’s reversed: violet outside, red inside.
Each extra reflection also loses more light, which is why the secondary arc is fainter.
✨ Tip for visitors: Come on a sunny morning or late afternoon, and let us show you the spots where Niagara’s rainbows make their daily appearance. It’s one of those moments where science feels like magic.