Editing Differential rotation (section)

== Surface level ==
For observed sunspots, the differential rotation can be calculated as:
<math display="block">\Omega = \Omega_{0}-\Delta\Omega \sin^{2}\Psi</math>
where <math>\Omega_{0}</math> is the rotation rate at the equator, and <math>\Delta\Omega = (\Omega_{0}-\Omega_\mathrm{pole})</math> is the difference in angular velocity between pole and equator, called the strength of the rotational shear. <math>\Psi</math> is the [[heliographic latitude]], measured from the equator.
*The reciprocal of the rotational shear  <math>\frac{2\pi}{\Delta\Omega}</math> is the lap time, i.e. the time it takes for the equator to do a full lap more than the poles.
*The relative differential rotation rate is the ratio of the rotational shear to the rotation rate at the equator: <math display="block">\alpha=\frac{\Delta\Omega}{\Omega_{0}}</math>
*The Doppler rotation rate in the Sun (measured from Doppler-shifted absorption lines), can be approximated as: <math display="block">\frac{\Omega}{2\pi} = (451.5-65.3\cos^{2}\theta - 66.7\cos^{4}\theta) \, \mathrm{nHz}</math> where {{mvar|θ}} is the co-latitude (measured from the poles).