A new mechanism of proportional electroluminescence (EL) in two-phase Ar has been revealed, namely that of neutral bremsstrahlung (NBrS), that quantitatively describes the photon emission below the Ar excitation threshold and non-VUV component above the threshold. This paves the way for direct readout of electroluminescence (S2) signals in two-phase TPCs, using PMT and SiPM matrices, in particular in dark matter two-phase detectors. In addition, this mechanism predicts the enhanced contribution of the fast component to S2 signal, which can affect the correct determination of diffusion coefficients and z-coordinate fiducialization in liquid Ar detectors. The NBrS effect has a universal character: it should be present in all noble and molecular gases. It may also explain the non-VUV components observed earlier in various light emission processes, in particular the primary and secondary scintillations in noble liquids in the visible and NIR range.