Abstract: Using day-to-day grid data cf ECMWF (European Center of Medium Range Weather Forecast) from 1980-1983,atmospheric energy is calculated here for a dry year(1981) and a wet year(1983) in Mei-yu (continuai rain in June-July)anomalies in middle and low latitudes of the East Hemisphere. An analysis aased on it diagnoses temporal variations of the energy characteristic of medium-range oseil lation,which is spectacularly in-phase for the entire troposphere as far as the total energy is concerned. There are significant difference in the quantity and the change of the energy between the dry year and the wet year either in terms of the Mei-yu itself or the period immediately before it,and the difference of the latter inputs to medium and long term forecasts of raininess in the Mei-yus.