VHF Propagation

[sfd119]

There's some nice VHF Propagation going on right now. From Spooner, I heard Wausau State Patrol Post and Eau Claire EMS. From Rice Lake I heard Duluth Gold Cross units.

VHF Propagation Map

 

[70cutlass442]

can someone please explain exactly what propagation is, how it works, and what influances it? Thanks!