Based on a numerical experiment carried out with a simple rectangular water area as an example, the paper discussed the developing progress of convection driven by surface cooling in aquatics waters with free surface quantitatively. 以简单矩形水域为例,利用数值实验方法,定量探讨了具有自由水面的养殖水域由于水面冷却而引起的对流演变的过程。