Refraction
* More refraction means the more spreading out of light and so they appear larger.
* Most refraction causes beams
  - depends on thickness
  - involves light.
  * Examples of waves include sound waves and light waves. Refraction is seen most often when a wave passes from one medium to a different medium. Different types of medium include air and water. When a wave passes from one medium to another medium, the wave will change its speed and its direction. For example, when a light wave travels through air and then passes through water, the wave's speed will slow down and it will change direction
* also causes illusions
  - some areas to be more prone to bigger waves than others
* appears to bend the float where it is visible beneath the water.
  - some light waves to bend and pass through the side walls
* change in direction of a wave because of a change in propagation speed
  - wave direction when waves pass from one medium into another
* changes the direction of the ray.
* depends on layers to increase in velocity with depth
* function of the observed pressure and temperature.
* is also the operative process controlling profiled rear projection surfaces
  - caused by sound entering the new medium at an angle
* is caused by the change in speed experienced by a wave when it changes medium
  - difference in the speed of the radiation in the two media
  - two effects
  - dependent on the speed at which light travels
  - due to the scattering of the light by the atoms that make up the material
  - nothing but bending of the light rays
  - performed on almost all complete eye exams
* is the bending of a light ray as it passes from one medium to another
  - ray of light
* is the bending of light as it moves from one material to another
  - it moves through different media
  - it passes from one medium to another of different density
  - it passes through an object
  - it passes through two materials of different density
  - cause by a speed change when it passes through different media
  - rays upon passing from one transparent medium to another
  - when it passes from one medium to another
  - sound waves from their original path
  - which is caused by changing speed
  - change of direction that occurs when the medium changes
  - effect on a wave when there are changes in a medium
  - process by which the eye bends light to form an image on the retina
  - when light passes through the object but is bent in the process
* link to a web page discussing refraction.
* occurs as light passes through small lenses seated at distant intervals
  - at surfaces or interfaces just as reflection does
  - because waves travel at different velocities in different media
  - four times, as the light intersects the vessel s inner and outer surfaces
  - when a light ray changes mediums
* occurs when light enters the eye through the cornea and lens
  - waves are bent by shallow water
* often continue to change through the teenage years into the early twenties.
* physical phenomenon
* refers to how a lens, such as a cornea, bends light rays.
* refers to the ability of the eye to focus light
  - bending or deflection of the light rays
  - deflection of a ray of light as it enters the eye
  - way the cornea and lens bend light rays to focus properly on the retina

### refraction:

Atmospheric refraction
* bends light rays passing along the earth's surface toward the earth
  - the rays so that they can pass over the horizon
* can change signal timing, causing position errors.
* causes the Sun to appear to rise earlier that it actually does
  - sun to become slightly flattened in shape
* depends on the zenithal angle and occurs for all instruments.
* is caused by the varying density of air with height
  - especially notable on cold clear nights
* makes everything seem slightly higher in the sky than it actually is
  - the elevation angles of distant peaks slightly larger