Moist adiabats with multiple condensing species: A new theory with application to giant planet atmospheres

TL;DR

This paper introduces a new, highly accurate formula for calculating moist adiabatic temperature profiles in atmospheres with multiple condensing species, applicable to planetary atmospheres including giant planets, hot Jupiters, and brown dwarfs.

Contribution

A novel, unified formula for moist adiabats that accounts for multiple condensing species, variable heat capacities, and converges with machine precision, extending applicability to diverse planetary atmospheres.

Findings

The new formula unifies existing methods and improves accuracy.

Application to Galileo probe data suggests strong downdrafts influence thermal profiles.

The model captures interactions among condensing vapors affecting lapse rates.

Abstract

We derived a new formula for calculating the moist adiabatic temperature profile of an atmosphere consisting of ideal gases with multiple condensing species. This expression unifies various formulas published in the literature and can be generalized to account for chemical reactions. Unlike previous methods, it converges to machine precision independent of mesh size. It accounts for any ratio of condensable vapors to dry gas, from zero to infinity, and for variable heat capacities as a function of temperature. Because the derivation is generic, the new formula is not only applicable to planetary atmosphere in the solar system, but also to hot Jupiters and brown dwarfs in which a variety of alkali metals, silicates and exotic materials condense. We demonstrate that even though the vapors are ideal gases, they interact in their effects on the moist adiabatic lapse rate. Finally, we apply the new thermodynamic model to study the effects of downdrafts on the distribution of minor constituents and thermal profile in the Galileo probe hotspot. We find that the Galileo Probe measurements can be interpreted as a strong downdraft that displaces an air parcel from 1 bar to the 4 bar level.