F or the first time on my trip, the precipitation was in the form of rain instead of snow when I was in Warsaw — but just barely, as the air was still bordering on frigid…
Partial Rainbow Over Warsaw
…but once this first round of precipitation ended, I was treated to a partial rainbow from the view of my hotel room.
How a Rainbow Forms
The visible part of the electromagnetic spectrum is comprised of the colors of red, orange, yellow, green, blue, indigo and violet — which is otherwise known as ROY G BIV. White light is composed of all of those colors at full intensity with regard to the additive color model of which red, green and blue are the primary colors.
When moisture in the form of precipitation is in the air and the sun is shining behind you, the droplets act as miniature prisms which refract the sunlight to create the colorful display which is perceived as a rainbow. More moisture and more sunlight results in brighter and more vivid rainbows.
I used to teach basic color theory; and the explanation above is a basic one.