The precipitation animation shows two maps. The top map is the climatological average for that month, ie the April map is the average of all the Aprill's from 1987 to 1992 when this data was available. The lower map shows the anomalies for each particular month and year. This is the difference between the long term average and the actual data for a single month. The top map shows a regular annual cycle caused by the changing position of the sun throughout the year. In addition the deep convective cloudiness brought on by the southwest monsoon is clear in the months of May thru September. It is interesting to note that the movement of the precipitation low over Africa only moves north-south, whereas the precipitation low over the Indian Ocean has and east-west component causing it to move right up the Bay of Bengal.
Click here to see an animated movie of monthly precipitation data.
Click here to see an animated movie of monthly mean & anomalous precipitation data.