Atmospheric phenomenon affecting TV and radio broadcasts

CMU Public Radio's broadcast tower in Mt. Pleasant.

CMU Public Radio’s broadcast tower in Mt. Pleasant.

If you’ve been having trouble recently picking up your favorite radio or television station over the air, you’re not alone. A phenomenon known as “tropospheric ducting ” is affecting broadcasts across the Midwest.

It’s causing distant signals to be received sometimes hundreds of miles away from their source, while at the same time making some local stations nearly impossible to pick up.

We asked CMU Public Broadcasting’s Transmission Supervisor John Martin about this rare atmospheric condition. He says it’s caused by different temperature layers in the air mass above Michigan, and it’s making radio and TV signals do strange things.

“They might skip over a certain landmass, or come to ground a little bit too soon,” Martin explained. “And in that case, you end up either getting distant signals you don’t normally get, really strong signals where they shouldn’t be quite as strong, or nothing at all.”

Some listeners and viewers have reported picking up distant signals from Wisconsin and Minnesota, while having problems receiving stations closer to home.

Martin says from an engineering standpoint, little can be done to rectify the situation, except waiting for the weather to change. That can sometimes take days.

Of course, CMU Public Radio listeners have another option: the free WCMU Mobile App. It’s available for download in both the Apple and Android app stores.