In our microgravity experiments for a near-critical mixing surface liquid jet it is observed that the liquid column is disintegrated with a certain, short wavelength at a relatively short distance from the nozzle exit. In the present paper, the underlying physics of this peculiar behavior are explored on the basis of a theoretical model, because the phenomena may be a candidate mechanism for the breakup of liquid ligament involved in turbulent atomization. It is found that the short-wavelength breakup is caused by the presence of the jet tip which contracts by the action of surface tension. The presence of the nozzle exit does not play any essential role on this disintegration, but at low pressure it leads to the excitation of long-wavelength breakup due to the Rayleigh type of instability wave which is generated from the capillary wave reaching the nozzle exit and reflecting.