Bubbles of hydrogen and methane carry soil radon, the main ionizer of surface air, into the surface atmosphere. As a consequence of ionization, light ion pairs are formed that determine the polar conductivity of the surface air; light ions’ aggregation with neutral condensation nuclei gives heavy ions, primarily responsible for the atmospheric electric field. As such, the density of hydrogen and methane subvertical flows will determine local electrical characteristics of the surface atmospheric air. Geological heterogeneities, deformations, and seismic and hydrogeological activity can change the density of hydrogen and methane flows. This book brings together extensive material from field observations to illustrate the possible use of atmospheric-electrical monitoring to solve problems of applied geophysics.