Engineering consultant Edd
Monskie says he’s been seeing an unusual number of instances of thermal
inversions that affect STL frequencies, and wonders if others have had the same
Writing on the Radio-Tech listserv,
he said the problem has been evident in Florida, Pennsylvania and Vermont.
“We have had thermal inversions all along over the years in
Florida,” he told Radio World in a followup email, “occasionally elsewhere.
This fall, for some reason weather-wise, it has hit in at least three markets.”
In simplified terms, “When you get a cool morning and then have the sun hit hard, you get a layer of warm air that affects all types of signals.” In the band
of frequencies devoted to studio-transmitter links, this could cause your link
to fade for a few seconds to a few minutes. In Florida through Texas, Monskie
says, he knows of instances where the problem lasted for an hour or more.
“It affects all bands in some way. One morning I had the
morning guy here in Pennsylvania call me in a panic as he pulled into our
parking lot that the FM was off the air. It wasn’t. I could hear it at my
house, but at the studios the whole FM signal was gone because of a thermal.”
If you’ve noticed that problem or have another comment about
your experience with thermal inversions, post it below.