Engineers Corner
4:26 pm
Tue July 24, 2012

TheEC: Tropospheric Ducting

An illustration of how Tropospheric Ducting works.

Here in Rhode Island, the heat and humidity interactions caused by Narragansett Bay can cause more stable ducting conditions, and that can impact our 102.7 signal noticeably for folks along the Bay. During warm days 102.7 can often be heard more strongly further north. At night, when it cools off, the effect tends to fade.

Since ducting is an atmospheric effect, it tends to be fairly unstable and unpredictable. Conditions like temperature, solar activity, proximity to the ocean, and wind can all create/disrupt a "duct" on a minute by minute basis. But there are some factors that allow for general prediction of the likelihood of ducting and where it can occur. William Hepburn's has daily "forecast maps" for the eastern United States, although these don't really show enough detail regarding the Bay itself. But it's interesting to watch the forecast shift with other weather conditions!