See:
http://home.cogeco.ca/~dxinfo/tropo.htmlThis site is great for predicting extended coverage due to tropospheric ducting. This type of propagation usually only lasts for a few hours to a day but can sometimes enable VHF/UHF communications up to 1,000 miles or more.
On
http://audio.liveatc.net:8012/zbw_test.m3u you can hear a lot of the controllers you normally can't hear (133.42, 128.75, etc.) since we have good propagation around the MA/RI/CT area.
Dave