Rainbow forms in waterfall at US national park, video goes viral

A video showing a rainbow forming in a waterfall at US' Yosemite National Park has gone viral on social media. Rainbows form in waterfalls when sunlight interacts with suspended mist droplets. As sun rays enter these tiny water particles, light is refracted, reflected off the back of droplets, and then refracted again, causing it to split into its component colours.