Exoplanet Cloud Condensation Phase Diagram

Atmosphere Parameters

Equilibrium temperature T_eq 1500 K

Lapse steepness R/c_p 0.24

Surface gravity g 20 m/s²

Metallicity [M/H] 1.0×

Condensate Species

Cloud Decks

Scale height H

— km

Active decks

0 / 6

How it works

This is a pressure–temperature (P–T) phase diagram — the same tool atmospheric chemists actually use, rather than a spatial render of the column. The atmosphere's own profile is a dry adiabat below 1 bar, isothermal above it:

T(P) = Teq · P^(R/cp)   for P ≥ 1 bar
T(P) = Teq             for P < 1 bar   (P in bar)

Each condensable species has a saturation curve in Clausius–Clapeyron form:

Tcond(P) = T0 · Z^k · P^(1/n)

Both curves are drawn directly on the diagram: the thick white line is the atmosphere, the dashed colored lines are each species' saturation curve. Wherever the atmosphere line crosses a species' curve, that species condenses — the crossing point is the cloud deck, found by the same bisection search each time a slider changes. The right-hand ruler converts each crossing's pressure to a physical altitude via the barometric relation z = H·ln(P₀/P), with scale height H = k_BT_eq/(μg).

Reading the diagram bottom-to-top is reading the atmosphere deep-to-high: refractory species (iron, silicate) cross the atmosphere line only at high pressure/temperature — deep, hot decks. Volatile species (water) only cross where the line is cold enough, which on a hot Jupiter may be nowhere in range at all ("all vapor"). This is the real mechanism (Fortney 2005; Morley et al. 2012) behind the layered condensation sequence inferred from transmission spectra of hot Jupiters and brown dwarfs.