On the Surface Waves of Sea

[摘要] On the surface of water such as an ocean, waves are produced by winds or a sudden change of atmospheric pressure, but they decay immediately after proceeding into a place where no such agencies are working. In such cases, besides these forced waves, there exist free surface wavcs which have generally the very long wave length and progress far from the disturbing centre. In this paper the author intends to discuss these surface waves approximately, considering the effect of viscosity and the dcflecting force of the earth's rotation which are assumed to be constant everywhere and obtained the results: (i) the period of waves becomes little longer than that of perfect fluid on account of viscosity, (ii) the amplitude diminishes exponentially for time and is proportional to the inverse square root of the distance from the disturbing centre, (iii) each particle of water surface describes a space curve whose projections on the horizontal and vertical plane are both ellipese, (iv) the phase velovity V and the group velocity U are both the functions of the distance from the centre and have the relation 2U=V at γ=∞.

[学科分类] 大气科学