The following is a verbatim from EK. So yes, dispersion and wavelength are related.
"All types of waves refract. The index of refraction for any substance varies slightly with frequency. Longer wavelengths (lower frequencies) move faster through a medium than shorter wavelengths (higher frequencies), and therefore bend less dramatically at the media interface. As a result, white light, which is made up of all the frequencies in the visible spectrum, is split by a prism in a phenomenon known as chromatic dispersion.'