We begin at high water vapour pressure, where you can see a wall of ice bearing down on this hapless little 20-micron pollen grain:
The water vapour pressure was duly lowered and the ice wall retreated, though the pollen grains still have little water droplet “zits” on them.
Finally, a couple of close-ups of the pollen grains at high water vapour pressure...
And low water vapour pressure. (I had to pump up the contrast on this one as it was pretty washed out.) You can see that the pollen grain has started to dry out internally, like a grape turning into a raisin.
So what does it mean? Er, we don’t know yet, as these images need to be analysed in conjunction with the bloke’s aerosol experiments on the pollen grains. His job is so cool. ♥