Earth Phenomena

The Earth is filled with unusual land formations and an array of all the different colors.  The interesting formations and colors don't grab the attention of most people on a regular basis.  This is because it's the normal everyday appearances that don't usually change.  There are, though, unusual formations and illusions that are results of  the way in which the Earth is positioned.  Two results that I will discuss are mirages and the concept of rolling uphill.
 

Mirages
In order to understand the formation of a mirage, we must take a look at the air and the different affects it has the closer it is to the Earth.  This air refracts from the ground.  Refraction, according to dictionary.com, is the change of direction of a ray of light, sound, heat, or the like, in passing obliquely from one medium into another in which its wave velocity is different.  This is the case in the air, relative to the Earth.  The closer the air is to the ground, the hotter the air is (especially in hot deserts), the smaller the reflactive indexes of the air becomes.  As light travels through the air, the more reflactive it is, the smaller the slope is of the light's travel path.  Take a look at the following diagram:
Refracion allows the path of light to travel in a curve similar to the figure on the left.







Photo taken from Physics World

In a mirage, the path of light is very curved.  The light from the sun is reflected and travels upwards, creating, in a sense, a "new light."  This light is refracted again, eventually this refracted light will reach the observer's eyes, creating a mirage.  Generally, this is how the mirage works, according to Physics World, Cheung.

Photo taken from Physics World


Rolling Uphill
This is what I find so interesting.  I've never heard of this until this year!  Apparently, there are plenty of places where you can go to experience this interesting occurance.  In these places, when you put your car in neutral, you find yourself rolling uphill!  This is done as a result of an obscured level horizon.  Normally, when you are driving, the way in which trees and surrounding objects are presented give you a reference of whether you are travelling uphill or downhill.  In some areas, trees lean slightly, allowing the human eye to see an uphill road, when in actuality, it is going downhill.  This results in the optical illusion of objects rolling uphill.

These areas have become very popular tourist places.  There are many different beliefs as to why things may roll uphill in these particular places, but ultimately, science has proven the above.  Some believe this occurs because of mysterious "magnetic or gravitational anomalies" or because it is an unexplainable paranormal phenomenon.  More discussion on this interesting situation can be found here (Rolling Uphill Illusion).

Philip Gibbs lists several different places where this strange situation occurs:


Contents:
Homepage
1. Earth Phenomena
2. Strange Ice Formations
3. Wonders of the Sky
Bibliography
Jessica Hunt, Physics 212- Section F01, University of Alaska Fairbanks
Monday, April 02, 2006