Physics Explained: Rainbows, Mirages, Color of Sky & Sunsets.
*To understand the phenomenon of rainbows, mirages, and the color of the sky and sunsets, we must first look at understand the concepts of how light and optics work.
*Speed of light in a medium is determined by the interactions between light and the atoms that make up any particular medium. Some terms to familiarize ourselves with are index of refraction and reflection. The index of refraction is in a medium, the ration of the speed of light in a vacuum to the speed of light in that medium. Reflection occurs when light traveling from a region strikes a boundary at an angle and produces a wave that is bounced off of that boundary.
*A mirage can occur on a summer day. When you are driving down the road you see a looks to be a reflection of an oncoming car in a pool of water. However, the pool disappears as you begin to approach it. This mirage is the result of the Sun heating the road. The extremely hot road heats the air above it and a thermal layering of air is produced, which causes any light traveling towards the road to gradually bend upwards. This makes the light appear to be coming from a reflection in a pool on the road.
Basically...a mirage is seen on the surface of the road. Light bends upwards into the eye of the observer and the bottom of the wave front moves faster than the top-creating the mirage.
*Another concept we must identify is dispersion. Dispersion is when white light separates into a spectrum of colors when it passes through a glass prism. White light that is directed through a prism is dispersed into bands of different colors. The different colors of light bend different amounts when they enter into a medium. Different colors of visible light have different speeds when going through a medium.
*A prism is not the only way of dispersing light. A rainbow is actually a spectrum formed when sunlight is dispersed by water in the atmosphere (light rain or humidity). Sunlight that later falls on the water droplets is refracted and because of dispersion each color is refracted at different angles. And back at the top of the surface of the water droplet some light fore goes internal reflection and on the way
out of the droplet the light is again refracted and dispersed.
Basically...a rainbow forms when white light is dispersed as it enters and reflects at the inside boundaries and exits through a rain droplet. And due to dispersion only one color from each raindrop reaches an observer-creating a rainbow.
Work Cited:
1. Glencoe Science, Physics Principles and Problems Text Book. (Our textbook)
1 comment:
Rachel your pictures are spectacular. Keep up the great work! It looks like you spent quite a lot of time on that.
Post a Comment