Introduction: How to Draw a Rainbow
In this detailed instructional video I draw a rainbow freehand, however I would recommend using the circle tool of whichever program you're using or a compass if you're drawing a rainbow on paper. Simply erase the excess of the rainbow when using a complete circle and you can easily conform it to any terrain. As for the color pallet this will vary but in my case I'm using 255 red, 255 red 128 green, 255 red 255 green, 255 green, 255 blue, 255 blue 64 red, 255 blue 128 red. I would highly recommend using more layers and a better gradient of colors as this will look more smooth.