Two typical atmospheres for cluster 16: one atmosphere with down-flow and one with up-flow in the chromosphere. The blue lines are average quantities for all pixels with a negative line-of-sight velocity at c_m = 10⁻³ and the red lines are average quantities for all pixels with a positive line-of-sight velocity at the same column mass. We show the τ = 1 distributions for the up-flowing (blue) and down-flowing (red) at a Doppler velocity of +5.4 km s⁻¹ for the Ca II H line.