Page:Types of Australian weather.djvu/36

32 is shown in full force in front of the anticyclone, which by the way has lost none of its energy since the previous day; the depression is well off the coast and on its way to New Zealand. This burster reached a velocity of forty-nine miles per hour, and lasted thirty-five hours.

TYPE XV.—THE BLACK NORTH-EASTER.

This is a somewhat uncommon but nevertheless well known type of weather on the coast about Sydney. Its characteristics are a very strong and persistent north-east gale, continuing day and night for two or more days; it has been known to last five days and nights, and it ends with the advent of a southerly burster. Its cause is found in an extensive col, the rear of one anticyclone being at rest over this coast, while another lies over the Australian Bight. If the grade is rather steep and the system at rest for several days, then the north-east wind persists with force proportionated to the grade, until the whole system moves forward; the southerly winds in the front of the approaching high pressure then displace the north-easter and the storm is over.

There have been no good examples of this type since weather charts have been printed here. Chart 33 shows the necessary forms of isobars, but the grade is not steep enough for a gale.