def wlrad2wnrad(wl, wlrad):
    """
    Convert radiance from units W/(cm2 sr cm-1) to W/(cm2 sr um).
    """
    wn = 1 / wl  # [um] -> [um-1]
    wnrad = wlrad / wn ** 2  # [1/um] -> [1/um-1]
    return wnrad * 1e-4