Rado noise is generated by conductor surface
discharges (corona), resulting in discharge current changes
at high frequency. Conductor corona is more pronounced
during wet weather and also, when there are insects,
contamination particles, etc., on the conductors. Therefore,
the radio noise levels are higher during wet weather then
during fair weather periods. The signal strength of the
conductorcorona generated radio noise is usually not
significant at frequencies above the band of AM
broadcasting stations. Evaluation of the radio noise at a
given location is recommended in terms of the ratio of a
radio station signal strength to the noise strength at the
same fi-equency (signal-to-noise ratio).