The atmospheric current system termed the global atmospheric electric circuit (GEC) is assumed to be driven by convective cloud generators located mainly at low geographic latitudes. A research investigation into the role of clouds at middle and high latitudes in the GEC, particularly low-level stratiform clouds, have led to an analysis of the electricity of Nimbostratus and Stratus clouds observed over 2005-2015 at the mid-latitude Geophysical Observatory in Świder, Poland (52.12 N, 21.24 E) and the Polish Polar Station in Hornsund, Spitsbergen (77.00 N, 15.50 E). The vertical, ground-level atmospheric electric field, current density and air conductivity available for the duration of the recorded cloud cases have been analysed, separately for the main types of precipitation: rain and snow for Nimbostratus, drizzle and granular snow for Stratus. The analysis of the atmospheric electricity parameters confirms previous results indicating differences in the electrical behaviour of raining and snowing clouds. The Stratus clouds seem to be passive elements in the circuit, and a raining mid-latitude Nimbostratus can potentially be an electric cloud generator which charges the GEC, but its contribution needs to be investigated in more detail.