Comet tempel-tuttle and the recent Leonid meteor shower

As one of the famous meteor showers the Leonid meteor shower had the most spectacular bursts in history. Since 1998 a new series of activity of the Leonids has been coming. What will it be in recent years and in the future? According to different references, the levels of the showers in history are reviewed and discussed in this paper. Especially, the diagram of CEOS (the Comet-Earth Orbits Separation) versus TE-C (the time gap of the Earth following the Comet) is analyzed. It is found that almost all the meteor storms are located in an inclined square, and the strongest storms are in a curved strip. The boundaries of the square have a slope of about 15 ms(-1). The sizes of meteoroids calculated from this velocity are also reasonable. This means that the particles colliding with the Earth have a limited velocity to drift off its original orbit. With larger CEOS, the longer time interval after the comet passage would be needed for a possible storm. The width of this square indicates that the stronger Leonid showers would never be seen on more than about four consecutive years. In one cometary return, the percentage of bright meteors will decrease year by year. These facts could be explained by a model of the formation of a cometary dust tall, including the motion, dispersion, and breaking up of dust particles. Prediction could be made with this square region. We may have Leonid showers in 1998-2000 with a peak in 1999, and after AD 2000, one has to wait another century before significant displays will once again appear.