The winds in the region of the atmosphere from 20 to 100 km elevation over the northern hemisphere are critically examined. The summer and winter temperatures are computed from the wind field with the aid of rocket mean pressure data and under the assumption that the wind field is geostrophic. The temperatures obtained are found to agree with direct observations. Thus the observed wind and temperature distributions are shown to be consistent. Possible causes of some of the observed seasonal temperature changes in different parts of the upper atmosphere are discussed. The zonal wind cross‐sections prepared in this investigation are compared with wind distributions published earlier and found to agree fairly well with them. On the basis of the wind distributions and of theoretical considerations, the circulation in the mesosphere and thermosphere is derived.

The large-scale changes in the 5-day mean 700-mb contour pattern associated with the onset of monsoon rams over different parts of the country are located with the help of charts for  the period 1957-1962.   The onset of monsoon over India and adjoining seas south of 15°N is associates with the disappearance of the premonsoon high over central parts of the country and the formation of the monsoon trough near 90°E at the 700-mb level, The formation of the monsoon low with the major axis in an east-west direction near about 20 N heralds the establishment of the monsoon over the entire country. Simultaneously the Pacific 'High' shifts northwards.   It is also noticed that the extension of rains over central parts of the country is associated with the  disappearance of the anticyclonic curvature In the 700-mb contour pattern over the region. In those years in which the monsoon gradually extends westwards over north India such Its extension is associated with the gradual shift westwards of the monsoon trough.

A brief review of some important synoptic methods of Medium Range Forecasting is presented  and the line of approach adopted in the present investigation is indicated.   An examination of the mean charts for the winter seasons of the six-year period (1956-61) has revealed the large scale pressure systems which have an influence on winter precipitation over north India for periods of 5-days or more. Some of the interesting and useful relations found between pressure pattern and the corresponding precipitation are presented. The influence of the large scale pressure systems on the fast moving daily disturbances is examined.

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