Question Pool -- Category E3B
What is the cause of gray-line propagation?
-
A.
- At midday the sun, being directly overhead, superheats the
ionosphere causing increased refraction of radio waves
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B.
- At twilight solar absorption drops greatly while atmospheric
ionization is not weakened enough to reduce the MUF
-
C.
- At darkness solar absorption drops greatly while atmospheric
ionization remains steady
-
D.
- At midafternoon the sun heats the ionosphere, increasing radio
wave refraction and the MUF
See answer.
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