This discharge is also responsible for radio noise, a visible glow of light near the conductor, an energy loss known as corona loss and other phenomena associated with high-voltage lines.
Water increases the conductivity of the air and so increases the intensity of the discharge.
Also, irregularities on the conductor surface, such as nicks or sharp points and airborne contaminants, can increase the corona activity. Aging or weathering of the conductor surface generally reduces the significance of these factors. The higher voltages at which modern transmission lines operate have increased the noise problem to the point to which they have become a concern to the power industry. In foul weather conditions, however, corona discharges can be produced by water droplets, fog and snow.