Abstract:The tronado weather on August 12,1993 in Jinn Province is analysed.The results show that there are many obvious expressions at surface wind frield,upper circulation situation,Q vector divergence,atmospheric stability and energy field,before tronado appearance and at erly period of tronado formation.They may provide forecasting information.

Abstract:The results of hail suppression have been examined based on the data of hail cloud radar echo and the characteristics of the falling hailstones.The values of radar echo top height,indensity and 30dbz strong echo height of hailcloud after the anti-aircraft gun operation are remarkably less than that of before the operation.The maximum diameter,number density,duration of hailfall,kinetic energy,masses,kinetic energy fluxes and mass fluxes of hailstone in the operation area less than that of the contrast area.

Abstract:The data of the rain and snow acidity and the chemical components in winter from 1985 to 1991 are analysed.The results show that the frequence of acid snow is different every year,but.it is loWer than that of the acid f rain iii the same season.The snow acidity is less than that of the rain.The negative relationship between the snow acidity and the cond.uctivity is very clear.The analysis of the chemical components of snow suggest f that the SO^2-₄ content is becoming more and more the Cl^- level tends to disctease,the NH⁺₄ is of in4inly positive irans.

Abstract:The standard verification method of CBS of WMO is introduced.The products of T63 model are verified with the method,and are compared with the model products of T42 and that of the Japan model as well.The results show that the useful forecast effectiveness can reach 5-6 days.The prediction error range is much less than that of the T42 model.

Abstract:Using the precipitation data of "94.7"torrential rain,a preliminary analysis to its geographic location and its temporal tendency is given. The results show that the torrential rain is characterized by high intensity,large areas and concentrative precipitation time.

Abstract:The torrential rain on July 12-13,1994 in Beijing is resulted from the interaction of westerly trough,sub-tropical high and typhoon low.The lower east south jet provided sufficent dynamics,thermodynamics and moisture condition. The interaction is very significant.

Abstract:Nonlinear -equation including four force items and other terms associated with preciPitation arc calculated.The results show that the formation of the heavy rainfall in July July 1994 in Beijing is a joint affect of typhoon and westerly trough.Especially.the centre of heave rainfall is in correspondence with the moisture convergence at the low level,and the maxinum precipitation of 12hours is relevant to the intensification of ascending motion and moisture convergence.The laplace term of temperature advection in the nolinear ω-equation is most contrihutive.

Abstract:First,using dingnostic variable T_σTσTσ

Abstract:The wet potential tendency equation is used to diagnose 700hpa potential height on July 12-13 in 1994.The results show that the differential latent heat advection term has an important effect on the develpment and movement of the typhoon low generated the torrential rain in Beijing.But the effect of relative vorticity advection is much less during the torrential rain.

Abstract:Using the scale-seperation method,the energy generation and transformation during a torrential rain in July 1994 in Huabei area are calculated,with the purpose of finding the characteristies of energy generation and .transformation before and during the torrential rain.

Abstract:Under the influence of westerly low level cold vortex,trOPical storm and subtropical high,the atmospheric circulation at the midlatitude of China changed from latitude pattern to longitude pattern in July 11 to 12 in 1994.Using the mesoscale numerical model (MM4) from PSU/NCAR, numerical experiments have been made to analyse the high level jet,low level jet,water vapor transport and westerly cold air,in order to study the interaction of weather systems and trigger off machenism of heavy rain.

Abstract:Based on the principle of geostrophic and deviation winds,the NWP interpretation project of wind forecast is established. Through a year forecast experiment and three years operational verification,an effective practical project has been proved.'