Ticker for October 14, 2002

                
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October 14, 2002   October 14, 2002   October 14, 2002   October 14, 2002


Freeze Across Parts of Northern, Eastern Oklahoma

Temperatures dipped below freezing at 19 Mesonet stations this morning.
While most of the freezes were light (30+ Fahrenheit), a few stations
dipped to 28F and below, which is defined as a "hard freeze".  The
following map shows which stations froze, for how long, and to what
temperature the thermometer dipped:




Cold Front Brings Back That Ol' Lonesome Moan

Ticker readers within a few miles of a railroad track may have noticed
"louder" locomotives since the recent cold front's passage.  This is
due to the acoustic enhancement brought on by the surface inversion.

Sound waves are broadcast from the source (train), and some waves make
it directly to your ear in a straight line (assuming no obstructions).
However, because sound waves travel slightly faster in the warmer air
aloft than the cooler air below, some waves that were originally
targeted to go above your above your head are bent back toward you
by the inversion.

Low-frequency waves (like those emitted by a train) are more affected
by this process than shrill tones.  The end result?  "Louder" trains!

This process is put into pictures (very clumsily) below.  The pink
tones represent warm air above an inversion and the blue tones, cool
air below.  The hypothetical train emitting hypothetical train noises
would be on the image's right hand side.