Physics Photo of the Week
September 28, 2012
Artificial Mirage
A
wood-burning stove with a dull flat top sits in the
foreground of this image. The background (in addition
to all the kitchen clutter) shows a white knob for the
dishwasher (across the room) plus a little bit of reflection
from the top of the stove. The top of the stove has a
dull finish. However, the stove had a fire in it
heating the top and the walls. The air immediately
over the top of the stove is considerably warmer than the
rest of the air in the room. As a result the grazing
light from the dishwasher knob is refracted and bent upwards
as if it were reflected from a perfectly polished
mirror. This is the same phenomenon that gives the
illusion of water on a pavement on a dry day PPOW
September 21, 2007) and reflections of shore features
on a lake (PPOW
September 28, 2007).
The photo at right shows an automated sequence
looking through the mirage. 
In the first
frame the camera is well above the level of the stove top,
and there is no mirage because the angle of reflection is
too large for the refractive index of the stove's hot
air. The next two frames show the results when looking
at a much more grazing angle. The complete refraction
of the light prevents the stove-top from being seen.
Notice that the other controls on the distant dishwasher are
also distorted due to the refraction by the hot air close to
the hot stove surface.
Physics Photo of the Week is published weekly during the academic year on Fridays by the Warren Wilson College Physics Department. These photos feature interesting phenomena in the world around us. Students, faculty, and others are invited to submit digital (or film) photographs for publication and explanation. Atmospheric phenomena are especially welcome. Please send any photos to dcollins@warren-wilson.edu.
All photos and discussions are copyright by Donald Collins or by the person credited for the photo and/or discussion. These photos and discussions may be used for private individual use or educational use. Any commercial use without written permission of the photoprovider is forbidden.
Click here to see the Physics Photo of the Week Archive.
