When moving center horizontally on a psychrometric chart, what type of heat exchange occurs?

Moving horizontally on a psychrometric chart represents a change in the specific humidity of the air while keeping the temperature constant. This means there is an exchange of moisture, which is associated with latent heat transfer. When the specific humidity increases, it indicates that moisture is being added to the air, which involves latent heat gain. Conversely, if specific humidity decreases, moisture is being removed, leading to latent heat loss.

Simultaneously, even though the temperature remains constant, the air may still gain or lose sensible heat as it interacts with other thermal energy sources. Therefore, when moving horizontally, latent heat is exchanged due to the moisture content change, and there can also be some sensible heat changes involved, making the overall process a combination of both latent and sensible heat exchange. This interaction explains why the correct answer includes both terms: latent, due to the moisture change, and sensible, as thermal energy can still fluctuate in other contexts despite the temperature on the chart remaining unchanged.