Editing Rossby wave (section)

===Rossby parameter===
The [[Rossby parameter]] is defined as the rate of change of the [[Coriolis frequency]] along the meridional direction:
<math display="block">\beta = \frac{\partial f}{\partial y} = \frac 1 a \frac d {d\varphi}  (2 \omega \sin\varphi) = \frac{2\omega \cos\varphi} a,</math>
where <math>\varphi</math> is the latitude, ''ω'' is the [[angular speed]] of the [[Earth's rotation]], and ''a'' is the mean [[radius of the Earth]].

If <math>\beta = 0</math>, there will be no Rossby waves; Rossby waves owe their origin to the gradient of the tangential speed of the planetary rotation (planetary vorticity). A "cylinder" planet has no Rossby waves. It also means that at the equator of any rotating, sphere-like planet, including Earth, one will still have Rossby waves, despite the fact that <math>f = 0</math>, because <math>\beta > 0</math>. These are known as [[Equatorial Rossby wave]]s.