The horizonatal extent of lightning channels reconstructed acoustically from several storms is significantly larger than the vertical extent. Furthermore, an examination of all the reconstructed lightning structure in each of three storms, one in Arizona, one in Colorado, and one in Florida, shows that the lightning activity tends to occur in layers 2--3 km thick. In the Arizona and Florida storms, there were two layers of activity. Temperatures at the lower boundary of the layers were near 4¿C and -18¿C in the Arizona storm and -11¿C and -39¿C in the Florida storm. In the Colorado storm, there was a single layer having a lower boundary near the 0¿C isotherm. Our interpretation is that each of the two layers in the Arizona and Florida storms is associated with a corresponding charged region in the dipole of the thundercloud charge distribution. We suggest that the single layer in the Colorado storm was a result of the dipolar regions being closer together in altitude.