The Green Ray

This summer, I was traveling with SAS Airlines.  The airlines added a tail camera view to the passengers' menu, so with a click on the screen we could choose to see the airplane flying some 40,000 feet above the ground.  What a cool feature!  

When watching the sunrise, I witnessed a rare occurrence of a green ray of the Sun.  I have heard about that phenomenon, but have never seen it.  It was astonishing to see; as a human, as a human, I just remained overwhelmed by the beauty of nature; as a physicist, I admired the refraction of light from a new perspective.  Here is the picture:

Green Laser Reflection and Refraction

 

Anytime you observe reflection and refraction, you get actually multiple reflections and refractions.  Any reflected or refracted ray becomes an incident ray and is once again reflected or refracted at the boundary.  The useful skill is then to recognize which ray is which one and select only the those needed for the experimet.

Rainbow

 A rainbow visible on Garden State Parkway, NJ

(Photos by Sr. T.)

Laser ray captured between two glass surfaces

 Photo 1. The laser ray is captured between two glass surfaces.  

 Picture 2.  The incident, reflected, and refracted rays are sketched.  Notice that the two refracted rays at the left are parallel (the same angle of refraction!)

Picture 3.  White A at the right side indicated an incident angle; the blue A shows a reflected one. All angles A are equal.  B in lower right corner is an angle of refraction, other B-angles are both incident and reflection angles. All angles B are equal.

Hydrometer submerged in water

The hydrometer is designed to measure a density of liquids.  The density is shown the liquid surface on the hydrometer's scale. 

Hydrometer presented in the picture looks like a broken one - part of it visible above the water surface seems to be disconnected. This is an effect of refraction.

Refraction on a prism

 

Photo by Reema

Blue laser: refraction at the air-glass boundary