The second law of thermodynamics implies a relationship between the net entropy export by Earth and its internal irreversible entropy production. The application of this constraint for the purpose of understanding Earth’s climate is reviewed. Both radiative processes and material processes are responsible for irreversible entropy production in the climate system. With a focus on material processes, an entropy budget for the climate system is derived that accounts for the multiphase nature of the hydrological cycle. The entropy budget facilitates a heat-engine perspective of atmospheric circulations that has been used to propose theories for convective updraft velocities, tropical cyclone intensity, and the atmospheric meridional heat transport. Such theories can be successful, however, only if they properly account for the irreversible entropy production associated with water in all its phases in the atmosphere. Irreversibility associated with such moist processes is particularly important in the context of global climate change, for which the concentration of water vapor in the atmosphere is expected to increase, and recent developments toward understanding the response of the atmospheric heat engine to climate change are discussed. Finally, the application of variational approaches to the climate and geophysical flows is reviewed, including the use of equilibrium statistical mechanics to predict the behavior of long-lived coherent structures and the controversial maximum entropy production principle.

中文翻译：

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气候系统和热力学第二定律

热力学第二定律暗示了地球净熵输出与其内部不可逆熵产生之间的关系。审查了为了解地球气候而应用此约束的情况。辐射过程和物质过程都对气候系统中不可逆的熵产生负责。以物质过程为重点，推导出气候系统的熵收支，以解释水文循环的多阶段性质。熵收支促进了大气环流的热机视角，该视角已被用于提出对流上升气流速度、热带气旋强度和大气经向热传输的理论。然而，这样的理论可能是成功的，只有当它们正确地解释了与大气中所有阶段的水相关的不可逆熵产生时。与这种潮湿过程相关的不可逆性在全球气候变化的背景下尤为重要，因为大气中的水蒸气浓度预计会增加，并且讨论了了解大气热机对气候变化响应的最新进展。最后，回顾了变分方法在气候和地球物理流中的应用，包括使用平衡统计力学来预测长寿命相干结构的行为和有争议的最大熵产生原理。与这种潮湿过程相关的不可逆性在全球气候变化的背景下尤为重要，因为大气中的水蒸气浓度预计会增加，并且讨论了了解大气热机对气候变化响应的最新进展。最后，回顾了变分方法在气候和地球物理流中的应用，包括使用平衡统计力学来预测长寿命相干结构的行为和有争议的最大熵产生原理。与这种潮湿过程相关的不可逆性在全球气候变化的背景下尤为重要，因为大气中的水蒸气浓度预计会增加，并且讨论了了解大气热机对气候变化响应的最新进展。最后，回顾了变分方法在气候和地球物理流中的应用，包括使用平衡统计力学来预测长寿命相干结构的行为和有争议的最大熵产生原理。并讨论了在理解大气热机对气候变化的响应方面的最新进展。最后，回顾了变分方法在气候和地球物理流中的应用，包括使用平衡统计力学来预测长寿命相干结构的行为和有争议的最大熵产生原理。并讨论了在理解大气热机对气候变化的响应方面的最新进展。最后，回顾了变分方法在气候和地球物理流中的应用，包括使用平衡统计力学来预测长寿命相干结构的行为和有争议的最大熵产生原理。