Gravity Waves. Consider a pattern of motion in which fluid elements move at an angle θ to the vertical. Show that for an atmosphere where the Brunt-Vaisala frequency is ωB the elements will oscillate with a frequency ν = N cos θ.
θ = potential temperature
v= N cos θ -desired frequency of oscillation of the elements.
N= Brunt Vaisala frequency
θ = angle in rads (I know it's confusing here but wikipedia linked theta for potential temperature and I don't know how to make equations yet).
The Attempt at a Solution
Is ωB supposed to be something?
So I know that the Brunt-Vaisala frequency is the buoyancy frequency, is it just a frequency with respect to the vertical?
In which case the answer is just to multiply N by cosθ? This could be it, but the part where they define N=ωB confuses me, though there is more to the question.