Electrostatic production of low frequency (~1 Hz) acoustic pulses associated with electrical discharges in thunderclouds has been theoretically described and experimentally observed et al., 1977; Balachandran, 1983>. The measured waveforms differ consistently with the theories in that the observed wave has an initial positive (or condensation) pulse followed by a negative (or rarefaction) pulse; whereas theories predicted only a negative pulse. The electrical heating of the air by positive streamer systems during the discharge is computed in this theoretical paper. This rapid (supersonic) electrical heating, although small (~10-6 T0), produces a positive pressure perturbation (~10-1 Pa), which when added to the negative electrostatic pressure perturbation generates an acoustic wave consistent with measured signals. A positive pulse always precedes the negative pulse in this model, and the positive pulse is always smaller in amplitude than the negative. The durations of the positive and negative pulses are similar. When more realistic models are employed, the observed signal can be related through theory to physical parameters in the thundercloud.