Dictionary:κ

{{#category_index:K|κ}} $\kappa$ Kappa.

1. The "angular" wavenumber, $2\pi$ times the wavenumber. Where a distinction is made, the wavenumber k is the number of waves per unit distance, the reciprocal of wavelength:

${\text{wavenumber}}={\frac {1}{\lambda }}=k={\frac {\kappa }{2\pi }}={\frac {f}{V}}$

where $\lambda$=wavelength, f=frequency, and V=velocity. Thus $\kappa$ is to wavenumber in the spatial sense as angular frequency $\omega$ is to frequency f in the time sense. Confusingly, both $\kappa$ and k are often called wavenumber, i.e., some authors use $\kappa ={\frac {1}{\lambda }}$ instead of the above.

2. Seismic usage often implies apparent wavenumber $k_{a}={\frac {1}{\lambda _{a}}}$, $\lambda _{a}$ being the apparent wavelength and V_a the apparent velocity. If this definition is used, k_a varies with the angle between the raypath and the line of measure (the line of the spread, usually).