How does the composition of atmospheric air affect psychrometric calculations?

Atmospheric air is a mixture of many gases, including nitrogen, oxygen, carbon dioxide, and water vapor. The composition of atmospheric air can affect psychrometric calculations, particularly when dealing with trace gases. However, for most psychrometric applications, the air can be approximated as a binary mixture of dry air and water vapor. This simplification allows us to use psychrometric charts and tables that are based on this binary mixture assumption.