226 Long Waves in Canals and Standing Waves in Closed Basins 



an atmospheric disturbance, which disappears after a certain time. It will 

 create deformations of the level which attain a maximum and return to its 

 original state of equilibrium by oscillations, when the disturbing forces 



20 



10 



Fig. 96. Surface approaching a steady state at the far end (exposed to the wind) of a rec- 

 tangular basin for a sudden variation of atmospheric pressure (P = 1) and for a sudden 

 wind (W '= 1). (Proudman and Doodson.) 



disappear. Proudman and Doodson have computed numerically two cases 

 which are graphically shown in the Figs. 96 and 97. Figure 96 shows how 

 a sudden atmospheric and wind disturbance respectively affects the level at 

 one end of the basin. In the case of the pressure disturbance (P = 1), the 



Fig. 97. Deformation of the surface at the far end (wind exposed) of a rectangular basin 



under the action of a gust of wind. (W gives the course and the length of time of the gust 



of wind in two cases.) (Proudman and Doodson.) 



