Python Plot -- Plot from Top X-Axis Down

I have some temperature dependent X-ray data like the one posted below. The ticks at the bottom from the x-axis represent the main peaks for a certain phase. So, for my data, I have a transition from one phase at low temperature to a new phase at high temperature. I am able to show the ticks for the low T phase and would like to show the ticks for the high T phase from the top of the axis down. What I have: I would like it to look like this, where the red ticks will be the ticks for the high T phase: I already have the data files, just cannot figure out how to plot from the top x-axis down. What I want: