What does Wet Bulb Depression depend on?

Wet Bulb Depression is a measure that indicates the difference between the dry bulb temperature and the wet bulb temperature. It is directly influenced by how much moisture is in the air, which is reflected in the wet bulb temperature, and the surrounding air temperature. The wet bulb temperature is determined by the principle of evaporative cooling, where water is evaporated into the air, leading to a lower temperature reading. Therefore, Wet Bulb Depression fundamentally relies on the relationship between air temperature and wet bulb temperature; as one increases or decreases, so does the other, affecting the degree of depression observed.

The other options, while they involve relevant meteorological concepts, do not directly pertain to the calculation or understanding of Wet Bulb Depression. For instance, relative humidity and air pressure may impact other aspects of humidity and temperature but do not specifically define the depression itself.