The day/night terminator has 4 shade levels going from light to dark |
- Twilight or dusk is where the sun is 6° below the horizon. The D layer (green line at right) is illumiated is this area and to 9° below the horizon.
- Nautical twilight the sun is 12° below the horizon; the horizon is still visible,
- Astronomical twilight sun is 18° below the horizon The F layer (red line at right) is illumiated is this area and to 20° below the horizon.
- Night
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The Magnetic Equator is shown as a black line around the 0 degree equator line
The Magnetic Equator is important for Transequatorial Propogation and the magnetic field strengths are believed to be important for Sporadic-E Propagation.
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