Discussions about the operation of atmospheric water generators (AWGs) often focus on relative humidity ranges alone. This is a flawed way of thinking which becomes confusing. The correct approach is to discuss machine performance at specific combinations of temperature and relative humidity (at a specific air pressure). The chart shows how the water vapour density in the air varies according to the temperature - relative humidity combination at constant air pressure. Water vapour density is the water resource available to an AWG. The water-from-air resource can be thought of in the same way as a stream, pond, or aquifer. The water-from-air resource increases with increasing temperature and relative humidity. Most places on Earth where AWGs are likely to be operated have water vapour densities of 4 to 21 grams per cubic metre of moist air (red, green, and purple zones on the chart). The data for the chart is from the Atmospheric Water Vapour Resource Table (SI).
I have been researching and developing drinking-water-from-air technologies since 1984. As a physical geographer, I strive to contribute an accurate, scientific point-of-view to the field.