An analysis of atmospherics for June, July and August, 1957

An account is given of the investigations of the observed weather associated with sferic fixes and the use of these atmospherics as a forecasting aid for the months of June, July and August, 1957. By considering the weather at observing stations that are within a distance of 30 miles of the sferic fix, in 55 per cent of the 94 cases that occurred, thunderstorm clouds of some precipitation in the form of showers, rain of drizzle were observed of which 13 per cent of the total observations. Vere idontifiod with actual thunderstorms. In only 4 per cont or cases was the sky less than half clouded. The atmospherics were found to be closely associated with low pressure systems and their associated troughs and front. 69 per cent of the extra-tropical depressions had associated atmospherics which in the majority of cases lay in the sector from N to ESE of the centre of the low. A strong and extensive outbreak ot atmospherics in an area was usually coincident with a sharp fall of barometric pressure and surface eyclogenesis or frontogonesis. There was an almost complete absence of sferic reports in high pressure systems.