Which expression correctly defines Elevation Factor?

Which expression correctly defines Elevation Factor?

• A. EF = R / (R + H + N)
• B. EF = R / (R + H)
• C. EF = (R + H) / R
• D. EF = R - H

Answer: (A)

Elevation Factor is the dimensionless multiplier used to adjust vertical measurements for the Earth’s curvature and atmospheric refraction along a line of sight. It’s defined as the Earth’s radius divided by the Earth’s radius plus the height involved and the refraction correction, giving a value just under one. This is why the expression EF = R / (R + H + N) is the correct form: the numerator uses the Earth’s radius, while the denominator adds the height term and the refraction term to account for how the path bends and stretches with distance. The other forms don’t fit because omitting the refraction term (or using subtraction or inversion) fails to produce a dimensionless factor that properly represents the small correction needed for curvature and atmospheric effects. In practice, this factor is used to adjust measured elevations so they reflect true elevations on the curved, refracting Earth.

Elevation Factor is the dimensionless multiplier used to adjust vertical measurements for the Earth’s curvature and atmospheric refraction along a line of sight. It’s defined as the Earth’s radius divided by the Earth’s radius plus the height involved and the refraction correction, giving a value just under one. This is why the expression EF = R / (R + H + N) is the correct form: the numerator uses the Earth’s radius, while the denominator adds the height term and the refraction term to account for how the path bends and stretches with distance. The other forms don’t fit because omitting the refraction term (or using subtraction or inversion) fails to produce a dimensionless factor that properly represents the small correction needed for curvature and atmospheric effects. In practice, this factor is used to adjust measured elevations so they reflect true elevations on the curved, refracting Earth.