Surfers call it shooting the curl, you hit the wave just right and can ride the wild surf through a tube of churning blue water. When conditions are right, even a weak VHF/UHF signal can shoot the curl and pop out hundreds of miles from where it started.
This is the phenomenon of “Tropospheric Ducting”. Here’s a video from WD0AKX that documents what happens when tropo is in full swing, along with a link that shows tropo predictions across the U.S.
