• F2 layer is a thin black line, often embedded in a red or green line.

• Propagation is best on frequencies having multiple horizontal reflecting red/green layers. (These are not actual reflecting layers. They are produced by multiple bounces between the F2 and the ground.)

• F2 layers with higher altitudes produce weaker signals than F2 layers with lower altitudes. (400 vs 350 km for example)

• A thick E layer (below 150 km) can produce excellent propagation when there is no F2 layer.

• Vertical "rain" indicates a weak reflecting layer with increased atmospheric noise.

• Vertical artifacts below 150 km are foreign or domestic broadcast stations.

Ionogram provided by UML Space Science Lab