Abstract:In this paper, the seasonal and non-seasonal features of the total cloud amount over Northern Hemisphere are analysed based on the data from 1966 to 1989. It is shown that the Northern Hemisphere has got two areas with bigger cloud amount, which are situated in the North Pacific and North Atlantic respectively, and also got one area with smaller cloud amout in the Northern Africa., The annual mean cloudness appears east-west oscillation. The areas with the bigger cloudness are just the areas with slighter interannual variability. And the position of the cloud areas vary obviously seasonally from winter to summer.The cloud amount in the high latitudes gradually increases from one month to another in the summer half year and decreases in the winter half year.The northerly and southerly moving of the areas with smaller cloud amount in the mid-lower latitudes is closely related to the northerly and southerly moving of the ridge at 500hPa subtropical high.

Abstract:In this paper , the comparati ve analysis on parameter fields between wide-range hail-fall and torrential rain are presented. It is evidently seen that the obvious variations exist in the fields between hail-fall and rain.These results are helpful for weather forecasting.

Abstract:In this paper, the relationship between the 500hPa subtropical nign features in the West Pacific and SLP (sea level pressure) in the northern hemisphere during June-August in summer based on the data of SLP, especially their temporal-spatial distribution and variation are analysed. An approach for the forecasting of the subtropical high features is developed based on the data of SLP.

Abstract:Some statistical properties of the meteorological satellite cloud image (MSCI) such as image gray distribution, information entropy, redundancy, two-dimentional Fourier spectrum, one-and two-dimentional autocorrelation functions of the original MSCI and the gray distribution, the information entropy etc, in differential domain have been studied in this paper. It shows that the gray distribution of MSCI is not completely random but is somewhat spatially correlative, whose spatial spectrum energy is mainly distributed in the low frequency area and the spatial correlation is rather looser in the differential domain but the redundancy still exists, thus producing a compression encoding method for MSCI, which could keep the information from losing.