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Abstract

Rocky planets orbiting nearby cool stars are extremely common, and next-generation space telescopes will allow us to begin studying them within the next few years. The extent to which we can make sense of these planets, let alone deduce whether any of them might host life, depends crucially on how well we can understand their atmospheres. This thesis develops a series of theoretical models for the atmospheric circulations of dry and tidally locked planets in particular, and of dry planets in general.,First, we motivate the detailed study of atmospheric dynamics for rocky exoplanets. We demonstrate that a tidally locked planet’s thermal phase curve, which is set by the atmospheric redistribution of heat between the day- and the nightside, can be used to measure a planet’s surface pressure and thus distinguish between planets with thick and thin atmospheres. Second, we develop a theory for the temperature structure and circulation strength of tidally locked planets. We show that the atmospheres of tidally locked planets act as large-scale heat engines, which allows us to predict their wind speeds and day-night temperature gradients. Our theory shows that rocky planets can exhibit large day-night temperature gradients at far bigger distances from their host star than can be explained by theories developed for hot Jupiters. Third, we extend our heat engine theory to atmospheres that are not tidally locked. We show that dry atmospheres primarily act to maintain a vertical, not a horizontal, temperature structure. We quantify this balance using entropy budgets and constrain the entropy production necessary for maintaining an atmosphere’s vertical temperature structure, which in turn allows us to predict the strength of frictional dissipation and surface winds across a wide range of dry atmospheres.

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