Tweaks
•Created by
the ionosphere “wave guide” cut-off effect of broad band lightning emissions
•At cut-off,
usually about 3 kHz, there is a dispersive effect that causes the frequencies just above cut-off to
be delayed in time, creating a
“tweak” sound
•Cut-off wave
length about 100 km. Ionosphere e-layer?
•May have
interesting HF propagation prediction possibilities
