12 & 266.3 & 1866.0 & 715.8 & 2667.5 & $<$360 & 19.5 & 16.3 & 0.560 & 0.59 & 4.95 & 0.998 & 1.000\
13 & 399.4 & 2933.9 & 865.2 & 3987.3 & $<$320 & 19.0 & 17.5 & 0.524 & 0.75 & 7.03 & 1.000 & 1.000\
14 & 719.0 & 5632.0 & 1146.9 & 7217.5 & $<$250 & 15.1 & 19.1 & 0.482 & 0.93 & 11.3 & 1.000 & 1.000 \[table:grid\]

The system that I study in this paper consists of an Earth-mass planet with a pure water vapor atmosphere orbiting at 1 AU around an active solar mass star. Using my atmosphere model, I calculate the 1D atmosphere structure between altitudes of 50 and 100,000 km assuming a zenith angle of 0$^{\circ}$. The zero zenith angle assumption is motivated by the assumptions made in Section \[sect:evo\] to calculate total atmospheric loss rates from the model results. The lower boundary altitude is largely arbitrary and our results are not sensitive to this choice since it is anyway negligible compared to the radius of the planet. At the lower boundary, I assume a gas composed of H$_2$O and HDO, with a temperature of 250 K, corresponding 