Penetration of the early morning rathmines' atmosphere by hot plumes

Priestley's (1956 ) theory of the bent over plume, applied to past radiosonde and upper wind observations at Rathmines, New South Wales, and using parameters relating to a projected power plant at Lake Macquarie near Rathmines, indicates that plumes from this plant would have failed to penetrate 1900 GMT surface inversions on about 18 percent of all days during the period of record. Most of the strong inversions with rather high tops are a ssociated with seaward winds which are presumably at least partly katabatic wind s from the Hunter Valley. In landward winds at 1900 GMT the theory indicates that plumes would have failed to penetrate 1900 GMT surface inversions on only about 2 per cent of days. Although only early morning inversions have been studied here, the possible effect of sea breeze inversions or stable layers on ceiling heights warrants special study at least in summer and early autumn. Approximate equations have been derived which considerably reduce calculations of the ceiling height of plumes for a wide range of values of emission velocity and temperature excess and stack radius.