A gravity wave occurs at the border between  one fluid and another, when a force upsets the equilibrium and gravity tries to restore  it, which produces a back-and-forth movement, or wave orbit.

当一种力破坏平衡并且重力试图恢复平衡时，重力波会发生在一种流体和另一种流体之间的边界，从而产生来回运动或波轨道。