Busch Stadium, 4:30 p.m., Central

The signal for the pregame show is strong and clear as I
leave the parking lot. Certainly no other baseball writer in
the country is heading away from Busch Stadium at this
moment. The plan during daylight is to go through the pretty
farmland in Southern Illinois - staunch Cardinals
territory - then cross back over the Mississippi River into
Missouri to accelerate the trip on an interstate highway.

On Route 3, near tiny Red Bud, Ill., 51 miles south of St.
Louis, news of Shane Victorino's back injury is transmitted
over the car speakers. The weather is clear, and the sun is
starting to dip toward the horizon. This is significant. As
I go over the big river on Route 150, I hear the first
distinct crackles of static.

AM (amplitude modulation) signals are susceptible to
interference from numerous objects, especially as they
weaken away from their source.

Within minutes, along Route 51 in Missouri, the signal is
virtually lost. The car is only 100 miles from the signal
tower, and the radio sounds as if it is broadcasting a
shower.

"This is going to be a pointless exercise," I say to myself.
"I'll be back at Busch Stadium by the fourth inning, looking
for a new story idea."

But anyone who has fiddled with an AM radio at night
understands that after the sun sets, the whole world comes
alive between 535 and 1705 kHz.

AM radio waves have unique properties that allow them to
travel round the globe, but their ability to stretch beyond
the horizon, instead of shooting off into space, has to do
with the way they interact with the upper layers of the
atmosphere, called the ionosphere.

According to Professor Arye Nehorai, the chairman of the
electrical and systems engineering department at Washington
University in St. Louis, the sun's rays ionize part of the
ionosphere, called the D layer, during the day, and the
layer reduces the strength of radio signals that hit it. At
night, without the sun's rays, the D layer effectively
disappears, and the radio waves can interact more easily
with the E layer, which propagates them more effectively.

"This allows the AM waves to bounce through the ionosphere
at night and travel longer distances than during the day,"
he said.

(End of Part 2.)