Celestial Navigation · Altitude Correction — Temperature/Pressure
Additional altitude corrections for nonstandard air temperature and barometric pressure are most significant for observations:
- AAt high altitude near the zenith
- BOf Polaris only
- CAt low altitudes, where refraction is large and variable✓ Correct
- DOf the Moon only
Explanation
Because refraction dominates at low altitudes and depends on air density, the nonstandard temperature/pressure correction matters most for low bodies; near the zenith refraction (and this correction) is negligible.
Authority: The Nautical Almanac, additional altitude correction tables
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