even although it is an old, it is good to read.
G4MWO NVIS Presentation
Given that NVIS - Near-Vertical Incidence Skywave is an important propagation mode on 5 MHz, here's the tiny URL for my NVIS Presentation in Google Docs.
To most people the phrase "tropical bands" bring a pretty clear picture to mind - a bunch of shirtless guys playing calypso music. But to experienced shortwave DXers those two little words express the most challenging and enjoyable part of the radio hobby. The phrase kindles memories of a DXer's best catches and favorite QSLs, of exotic stations, music and of early morning listening sessions. (Don Moore)
I like the "Tropical band" name for new 60m allocation. (OK1RP)
Effective from 1st Jan 2017 please paper QSL via OM-bureau only.