Abstract
Some studies on the pressure distribution and its changes in typhoons revealed that the minima of the center pressures of typhoons are divided into four groups. This seems to come from the difference in the mechanism of development of typhoons.
Following each life stage of a typhoon, the isobar profiles show very interesting deformations which are almost the same with the changes of appearance shown by the water spout trunk in its life stages. From those pressure profiles the author pointed out the importance of the eye wall on the mechanism of typhoon development in its immature stage.
