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