Relations between the generator currents in a thunderstorm cell and the currents to the ionosphere are examined. The effects of variations in the breakdown electric field below the lower charge center, heights of the upper and lower charge centers, generator currents and geometry, and the conductivity profile of the cloud, the surrounding air, and the ionosphere are examined. It is shown that for clouds transferring negative charge to ground in cloud-ground flashes, the major factor controlling the ratio of the current to the ionosphere to the generator current is the fraction of the major discharges that are between the lower charge center and ground. This parameter serves to organize data for a wide variety of assumptions about the parameters studied. The precipitation current between the lower charge center and ground does, however, remain an important variable which must be considered. It is shown that for both storms that are very active and for those that do not produce lightning, the most important single variable controlling the ratio of the current to the ionosphere to the generator current is the height of the lower active center. Because low altitudes correspond to high currents to the ionosphere, high-latitude storms and those in the winter hemisphere are relatively more important than had been thought. It is shown that though the ionospheric conductivity from 40 to 120 km is very important in controlling the electric field and current density waveforms above the cloud, it has a negligible effect on the total current to the ionosphere.