The wokers of the Meteorological Research Institute and the Osaka District Observation make their effort to establish the critical value which discriminates between shower and thunderstorm. One of the methods which determine this value, is published in the Soviet meteorological journals by N. F. KoTOV. His method is seemed to be convenient in order to make the discriminative study of shower and thunderstorm from the material which observed the height of radar echoes.
The critical values of shower and thunder s t orm are determined by the materials obtained by radars of the Meteorological Research Institute and the Osaka District Observatory. The value of the former is published by author and Ichimura in 1961, and the latter is defined in this paper.
By the use of the material of radar echoes obtained in the region of Osaka in 1955, the critical value in the case of a covered uniformly air mass is equal to 15.0°C in temperature, the value of Osaka approximate to the value which is estimated by the use of the materials of radar observation in 1956 and 1958 at the Meteorological Research Institute, that is, -15.6°C.
In the case o f the thunderstorms which are accompanied by the fronts, the critical value has the temperature 9.8°C and obtains higher value by about 5°C than the above-mentioned cases.
In our territory, when the tops of radar ech o es pass the level of the isothermal layer -15°C--16°C, the convective clouds in agreement with radar echoes are determined as thunderstorms, but the thunderstorms in the frontal zone occur at lower layer.
View full abstract