The trace of visible scattering in air induced by a CW1.06m laser beam has been observed inside the cavity of a Nd: YAG laser. The scattering light has a continuous distribution covering the visible spectral range, and the threshold of laser beam power density required for this effect was found. When the period of laser action was reduced to the order of millisecond by using a mechanical rotating switch within the cavity, this effect could still be observed.