We present and assess a simple equation for saturated vapour pressure over water and ice. The equation does not rely on an explicit integration of the Clausius–Clapeyron equation, but instead uses the equality of the Gibbs functions of the vapour and the liquid or ice in equilibrium. The resulting equation is simple, physically consistent with standard thermodynamic assumptions, uses only basic physical parameters, and is at least as accurate as commonly used empirical fits. It is further shown that the finite volume of liquid water has a negligible effect on the vapour pressure. The main variation from accurate tabulated data results from the variation of vapour and liquid isobaric heat capacities. Nevertheless, it is shown that, for the purpose of accurate calculation of saturated vapour pressure, this can usually be ignored.

中文翻译：

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精确，简单的方程式，用于水和冰上的饱和蒸气压

我们提出并评估了水和冰上饱和蒸气压的简单方程式。该方程式不依赖于克劳修斯–克拉珀龙方程式的显式积分，而是使用平衡状态下的蒸气和液体或冰的吉布斯函数的等式。所得方程很简单，在物理上与标准热力学假设一致，仅使用基本物理参数，并且至少与常用的经验拟合一样准确。进一步表明，有限体积的液态水对蒸气压的影响可忽略不计。准确列表数据的主要变化是由于蒸气和液体等压热容量的变化引起的。然而，已经表明，出于精确计算饱和蒸气压的目的，这通常可以忽略。