The Science Behind Rainbows: What Causes Them?
A rainbow is a multicolored arc made by light striking water droplets. ... The most familiar type rainbow is produced when sunlight strikes raindrops in front of a viewer at a precise angle (42 degrees). Rainbows can also be viewed around fog, sea spray, or waterfalls.
The science behind rainbows
The higher the angle, the more complicated the rainbows are. The rainbow formed by a single column of light has seven horizontal and six vertical strands. That angle is crucial in determining the color of the horizontal part of the rainbows. With seven strands, the horizontal part of the rainbow is orange. With six strands, it is green. A rainbow can be seen around mist, sea spray, and waterfalls. To see a rainbow around mist, you have to know that it will be diffuse, because the sun is behind you. The mist must be relatively shallow, not as thick as a fog. If you hold your hand up in front of you and don't move your head, you should see only a thin, diffuse layer of mist. Then, if you move your head, a rainbow will appear.
What causes rainbows?
Rainbows are produced by the interaction of sunlight and water droplets, clouds and rain. During a rainbow, light is scattered into different colors, which scatter light in different directions. For example, violet light scatters to the right (away from the sun), while red and green light scatter to the left. In the case of rainbows, the specific angles of the scatterers determine the color you see as the arc. The relationship between water droplets and the sun at different times in the day affects the colors we see in the arc. For example, at dawn and dusk, which are times of low and high sunlight, we see two main types of rainbows: penumbral (bulbous at the center) and umbral (the arc at the top is on the side of the droplet).
Types of rainbows
Rainbows can be produced by different refraction of sunlight, or bending of the path of a beam of light. Theoretical models based on light-wave interactions predict that this phenomenon can occur for any angle between 0 degrees and 180 degrees. This is why the rainbow arcs are named after this angle. Some rainbows are very wide. Shorter rainbows: This is a rainbow produced by the refraction of sunlight by the water droplets at an angle less than 180 degrees. They are typically shorter than 180 degrees, with color changes confined to the edges of the loop. The profile of the rainbow is a thin, arch-shaped arch with color changes on the way out to the sides of the arc, which is called a backward bow.
It's important to realize that rainbows aren't a one-time phenomenon. Unlike the bow seen after a bow shot, rainbows aren't a specific shape that appears and disappears. It's actually a wave of light from water droplets reflected in the sky, making each rainbow a little different. Unfortunately, we can't predict the exact color of a rainbow, since its appearance depends on the distance the sun is from the observer. Rainbow colors can also vary over short distances due to the characteristics of the environment the raindrops are in, as well as the exact angle of reflection. I recommend the experiment for kids, who are at a natural age to see and understand the rainbow. To see them, find a bright sky and a raindrop-covered window.