Some “rainbows” aren’t rainbows at all

 

CIRCUMHORIZONTAL ARC vs RAINBOW vs IRIDESCENT CLOUD vs “SMILE” ARC

Some “rainbows” aren’t rainbows at all — they’re sunlight taking different paths through ice crystals or tiny droplets, so the colors show up in totally different places in the sky.

Circumhorizontal Arc (top-left)
This happens when sunlight passes through flat, plate-shaped ice crystals in high cirrus clouds and spreads into a bright, horizontal band of color. It needs the Sun to be very high in the sky.
High cirrus clouds, midday sky

Rainbow (top-right)
A true rainbow forms when sunlight enters raindrops, reflects inside them, then exits—separating into colors. It appears opposite the Sun with rain or mist in the air.
After-rain sky, Sun behind you

Iridescent Cloud (bottom-left)
These pastel patches come from diffraction—light bending around tiny, similarly-sized droplets/ice crystals in thin clouds, usually near the Sun. It’s more “painted” than arc-shaped.
Thin cloud edges near the Sun

Circumzenithal Arc (bottom-right)
This is the upside-down “smile” arc, caused by sunlight refracting through ice crystals like a prism. It sits high overhead and often shows up when the Sun is lower (morning/afternoon).
Overhead icy cirrus, lower Sun angle