Did you know that you never see the same rainbow as somebody else? That's because you view the rainbow from a different angle than others, which means you see the light interacting with completely different water droplets than the person next to you.
Another thing you might not have known about rainbows is that they form complete circles. Although they look like arcs (half-circles) most of the time, this is because the ground cuts off your line of sight with the rest of the rainbow.
NASA explains, "from the air, the entire 360º circle of a rainbow is more commonly visible."
Because water droplets are more prevalent in higher altitudes of the atmosphere, you'll also notice that rainbows are their strongest in the sky. As you follow their arcs down to the sides, they begin to fade from view because of the lack of water droplets at lower altitudes.
Rainbows exist because as light moves through water droplets, the water distorts the light. In some cases, the distortion can even cause "double" rainbows.
Physics makes rainbows possible, so after reading this, perhaps you will have a newfangled respect for these beautiful shows of nature.