= Magnetic dipole inclination versus latitude
{title2=$\tan\iota=2\tan\lambda$}
For a centred <magnetic dipole moment> pointing toward geographic south, the field at northern latitude $\lambda$ has northward component $B_N=B_{\rm eq}\cos\lambda$ and downward component $B_D=2B_{\rm eq}\sin\lambda$. These follow by resolving the <magnetic dipole field> into local radial and meridional directions. The downward inclination is therefore $\tan\iota=B_D/B_N=2\tan\lambda$, while the magnitude is $B_{\rm eq}\sqrt{1+3\sin^2\lambda}$. This ideal aligned-dipole model has no eastward component and does not capture actual geographic departures of the geomagnetic field.
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