- A condition prevalent in the troposphere that results in VHF (very high frequency) and UHF (ultrahigh frequency) transmissions being received at very long distances. This is because certain layers of troposphere are bound above and below by layers that have different refractive indices. They confine and propagate abnormally high proportions of VHF and UHF radiation, giving freak long-distance communications and radar pickup ranges. The thickness of such layers is seldom more than 300 ft (100 m).The reflected signal in the second case will travel over a longer distance than in the first case.
Aviation dictionary. 2014.
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