In a dipole approximation of the Earth's magnetic field, the total field intensity at magnetic latitude (lambda) is given by B = B_eq x sqrt(1 + 3 sin^2(lambda)), where B_eq is the equatorial field strength, and the magnetic inclination (dip angle) I is related to magnetic latitude by tan(I) = 2 tan(lambda); the location where the horizontal (H) and vertical (Z) field components are equal corresponds to an inclination of 45 degrees, since tan(I) = Z/H = 1 at that point.