Just take a garden hose with your back to the sun and spray. You'll make a rainbow.

A rainbow is a full circle of light centered around the point opposite the sun, but grounded we can only see the arc above the horizon. You can only see a rainbow with your back to the sun.

“Life is like a rainbow, You need both the sun and the rain for colors to appear through dark clouds.” ~ Tom Baker

I'm kind of a germ freak. When I get on a plane, I spray my seat and everything with Lysol Disinfectant Spray.

And lo! In the dark east, expanded high, the rainbow brightens to the setting sun.

I know that if odour were visible, as colour is, I'd see the summer garden in rainbow clouds.