Pulse characteristics of single barrier discharges as well as parameters of charges accumulated on the surface of a dielectric under the atmospheric pressure in the “needle-(0.1–2.0)-mm air gap-polymer barrier-plane” system are investigated. It is found experimentally that for the positive polarity of the needle, the voltage for the discharge initiation is higher than in the case of the negative polarity by ∼25–35%. The reversal of the needle polarity from negative to positive increases the amplitude of the discharge current and the accumulated surface charge by ∼1.5–3 times. For the positive polarity of the needle, the discharge is governed by a streamer mechanism, while for the negative polarity, the discharge is initiated by the formation of a single Trichel pulse. The single pulse regime is observed for the discharge current up to a certain electrode gap dCR. For the positive needle and for air gap width dair > dCR ≈ 1.5 mm, a multipulse burst corona is formed, while for the negative needle and dair > dCR ≈ 0.9 mm, a damped sequence of Trichel pulses evolves in the system.