Originally Posted by Yooper
But that's not so. Water evaporates out of barrels in a lower humidity environment, and reduces the volume. I don't know about beer, but this is true of distilleries and I've seen it myself. That's the "angel's share". In a higher humidity environment, it's about equal water and ethanol, but in a lower humidity environment, it's proportionately more water that is lost.
This. We took a tour of the Stranahan's Distillery in Denver, and the barrels in the aging room are continuously misted with water. Given Denver's extremely dry environment, it was explained to us that this is required to prevent the angels from getting more than their share.