The broad characteristics of the North-west Australian Cloud Band, frequently observed across the Australian continent, are outlined. The cloud in the Band is most frequently first apparent within approximately 5" latitude and 17" longitude of 12"s 100"E, and may extend from there for several thousand kilometres, typically towards the east-south-east. It is found to be most in evidence during the winter months. Various atmospheric features associated with the development of the Cloud Band are discussed.

There is ample contemporary evidence that most meteorological thermometers in Australia were not exposed in Stevenson screens until very late in the nineteenth century, and in many places not until well into the twentieth century. There is also evidence, from a long-running comparison at Adelaide, that mean temperatures in a Stevenson screen are lower than in an open stand in Australian conditions. Thus, there are strong grounds for expecting that nineteenth century, and some early twentieth century, Australian temperatures are biased warm, relative to modem exposures.

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Up to 30 months of near-surface anemograph records have been examined from 13 locations in and near Melbourne, Australia, to determine the wind patterns which existed during prolonged periods of light winds (at least 3 hours at 2 m s-' or less). A coherent katabatic wind system was found to develop in at least part of the monitored region on approximately 30% of nights. The flow broadly followed the slope of the basin surrounding the city, with a strong flow down the main river valley, and was partly reinforced by a land breeze in bayside areas. Other valleys also acted as channels for these winds. The general tendency of these katabatic winds was to converge towards the central business district and the northern part of Port Phillip Bay adjacent to the city centre. Where winds from different directions interacted, one of the winds dominated or successive replacement occurred causing the wind direction to vary considerably during a period.There were indications that in the presence of low-level stability with a synoptic gradient wind between east and north, the gradient flow may be deflected around the major topographic barrier to the northeast of the city. The existence of such a situation would have major implications in terms of air quality due to the possibility of pollutants being recirculated in conditions when vertical diffusion was very limited.

During the last week of June 1978, Melbourne experienced a prolonged period of stagnation over the city, resulting in high levels of air pollutants. Internal Froude numbers through the period ranged from approxjmately 0.1 to 0.3, indicating that flow in the area should be strongly stratified. Wind patterns determined using data from thirteen anemographs within and immediately adjacent to the city revealed a pattern of eddies across the city each afternoon in a 'cavity' in the lee of upstream topography. That pattern evolved with time, and changed between days as the controlling meteorological conditions altered. The available mean sea level pressure data from the region for the same times indicated perturbations in that field which were consistent with the observed wind patterns.The eddy patterns were replaced at the surface overnight by katabatic winds as cooling took place and a ground-based inversion became reestablished. However, mean sea level pressure data and the anemograph records suggest that the eddy pattern may have continued overnight, aloft.Considerable recycling of air occurred, both within individual circulations and by wind reversal between daytime and nocturnal regimes. This aided the persistence of high pollutant concentrations.