To create a rainbow, is sunlight bouncing off the outside of a raindrop or the inside of raindrop?

i think it would have to be inside

Explanation:

bc the light has to be refracted (aka has to be inside water)at a angle to see a rainbow with are eyes

that tool is called an altimeter which measures your altitude which can be used to tell which atmosphere you are currently in, including the stratosphere.

hope this ! : )