Much like the swamp coolers my parents used when they moved to California. They worked in that dry air as the cooling comes from evaporation. Here in Florida they would just add to the humidity. Not that you can add anything to 100%. At least as it warms up durning the day it drops into the 80 percent range. 84 degrees and 82% right now at 10 oclock.
Anything that cools the air going across the unit makes a large difference