(The following article by Chuck McGinness was posted on the Palm Beach Post website on March 25.)
PALM BEACH, Fla. — Weird forces in the atmosphere created confusion for Tri-Rail commuters Thursday.
A weather condition known as tropospheric ducting disrupted radio signals along the 71-mile Mangonia Park-to-Miami corridor, causing early morning trains carrying thousands of passengers to run up to 90 minutes late.
Normally, radio signals travel a short distance before bouncing off the troposphere, the lowest of the three levels of the Earth’s atmosphere.
But a temperature inversion created by the unusual high-pressure system apparently deflected signals far and away.
Radios designed to operate over a 30-mile radius will transmit for 1,000 miles during a tropo-ducting incident and turn normal chatter into a mass conference call, with everyone speaking at once, Tri-Rail spokeswoman Bonnie Arnold.
With safety at risk, early morning trains slowed to 15 mph. Delays were reduced to 20 minutes later in the morning.
“If dispatchers can’t track trains, trains can’t run at normal speeds,” Arnold said.
CSX Transportation, which dispatches freight and passenger trains on the South Florida corridor, experienced similar problems in the Lakeland area, spokesman Gary Sease said.
A cold front that stalled over the Lake Okeechobee region contributed to the density differences in the atmosphere, National Weather Service meteorologist Tom Warner said.
In some instances, tropo-ducting can be beneficial, because it expands the range of weather radar.
But there also are disadvantages, such as increased ground clutter on radar screens.
“In (Tri-Rail’s) case, it doesn’t sound like it was too good,” Warner said.