Rainbow Curve, Rocky Mountain National Park
Rainbow Curve, a scenic viewpoint on Trail Ridge Road in Rocky Mountain National Park, sits at 10,875 feet above sea level and offers incredibly expansive views of Horseshoe Park, Alluvial Fan, Hidden Valley Creek, and the Beaver Ponds. There are plenty of accessible vault restrooms and free viewfinders, but be aware that the parking area fills up fast.
The Rainbow
A rainbow is a circular pattern of reflected light from water droplets, with each individual droplet dispersing the light and then reflecting it back at multiple angles. The radius of the rainbow is determined by the refractive index of the water droplets, which is the amount of refraction that happens as the light passes from air to water.
Colors of the Rainbow
The colors in a rainbow are a mixture of wavelengths, or colors, of the light that come from the sun. These wavelengths are called spectral colors. Each color has its own unique wavelength. When they are superimposed, the spectral colors look white, but when the color is viewed as a whole, they appear to split into distinct hues (or "colors") that are recognizable by human eyes.
Reflection and Refraction
It's the reflection of each individual color that gives the rainbow its distinctive appearance. The refraction of each color causes it to bend slightly differently than other spectral colors. This bend causes the colors to separate and become visible. When the refraction of each color reaches a certain angle, they break off into different wavelengths and appear to be a new color. This is a kind of interference between different wavelengths, which is also known as scattering.
Theories of the Rainbow
Some theories of the rainbow suggest that each color is a part of a single wavefront, which is the path of a single ray of light. This is a mistake because waves do not have a single, fixed direction.
Refraction and Reflection of Light
The color of a rainbow is caused by the refraction and reflection of light, which causes it to bend and bounce at multiple angles. There are many types of refraction, but the most common is that of a refractive wave. This refraction causes the ray of light to appear to be "bent." The reflected ray of light, on the other hand, appears to be "bouncing back" from the surface it is reflected off. This type of refraction is sometimes called a prismatic refraction, since the waves that form the reflected and refracted rays are shaped like a prism.
Chromatic Refraction
Another type of refraction is called a chromatic refraction, and it produces the distinctive color separation in a rainbow. The chromatic refraction is caused by the density of the water droplet, which causes each color to bend its light path slightly differently than other colors. The minimum deviation in the chromatic refraction is about 138°, which is the same as the angle of reflection from a surface. This is why the colors of the reflected and refracted rays seem to be split, even when they are both reflecting and refracting at the same time.
