Left: density of H₂ as a function of radius for IRAS4A. The black line indicates the density power-law from the dusty model, while the green and red points indicate the ortho and para-H₂ densities respectively for each ratran cell. Middle: temperature as a function of radius for the same model as the left plot, where the black line is an interpolation on a fine grid from the dusty model and the red points are the temperatures for each ratran cell interpolated from the same model. Right: the radius of the continuum τ = 1 surface (black) as a function of frequency. The H₂O 1₁₀ − 1₀₁ (solid red), 2₁₂ − 1₀₁ (solid blue), 1₁₁ − 0₀₀ (dashed red) and 2₀₂ − 1₁₁ (dashed blue) lines are all indicated with horizontal lines at the appropriate frequencies.