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An asymmetric surface-barrier discharge induces a unidirectional gas flow of several meters per second near the electrodes. The mechanism of how the discharge induces the gas flow is investigated experimentally by changing the electrode configuration from asymmetric to symmetric. The peak values of the discharge current and the discharge patterns depend on the polarity of the applied voltage in the asymmetric electrode configuration. When the exposed electrode is an anode (negative-going cycle), positive streamers extend over the dielectric above the buried electrode, and relatively large discharge current pulses flow. The momentum transfer from positive ions to neutral molecules occurs at the head of the streamers, where the electric field is strongest. Thus, the surrounding air is pushed with the extension of the streamers. When the exposed electrode is a cathode (positive-going cycle), a weak light emission is uniformly observed above the buried electrode. This light emission results from the electron impact excitation of gas molecules; thus, it does not indicate movements of the positive ions. Therefore, the momentum transfer during the negative-going cycle is dominant, and the unidirectional gas flow is induced in the direction of the extension of positive streamers.