Abstract:Along with the rapid development of economy and urbanization, atmospheric aerosol pollution is becoming worse. It is becoming a practical matter to distinguish haze and fog, and also an urgent issue need to be solved. In the past the operational standard by using relative humidity to discern fog and haze is commonly on the low side over the southeast coastal provinces. To distinguish fog and haze should be based on the change of influencing weather system combining other influencing factors. According to the new researches on aerosol in the recent years, the main water soluble particles less than 0.1μm diameter in the atmosphere are mainly composed by vitriol ammonium, while large than 1μm diameter are sodium chloride. The relative humidity for those matters is approximately 80%, so it is suggested that the weather phenomena, the visibility deterioration caused by atmospheric turbidness resulting in blur of visual field, is determined as haze when relative humidity is less than 80%, while as fog when relative humidity is large than 90%, and as the mixture of haze and fog the main constitutes are still haze when the relative humidity is between 80% and 90%. It is also suggested that to set down as soon as possible the ash haze index and its warning method, to develop the study on method of predicting and warning ash haze weather and to construct the operational platform, to open up the field of meteorological services, putting the products of environmental meteorology into public service.