Relative humidity is typically lower on which type of slope?

Relative humidity tends to be lower on south aspects due to the orientation of the slope in relation to the sun. In the Northern Hemisphere, south-facing slopes receive more direct sunlight throughout the day, causing increased temperatures and resulting in lower relative humidity. This is because warmer air has a higher capacity to hold moisture, thus making it less humid.

In contrast, north aspects receive less direct sunlight and tend to be cooler and moister, generally leading to higher relative humidity levels. This difference in solar exposure directly affects the moisture levels in the air, making the south-facing slopes typically dryer. The other aspects—east and west—also experience some variation in humidity based on sunlight exposure but to a lesser extent compared to the stark differences observed between south and north aspects. Therefore, it's the combination of increased solar heating and lower moisture levels that defines the relative humidity on these slopes.