Why can high-pressure systems lead to poor visibility at low levels?

High-pressure systems are characterized by descending air. As this air moves downward, it compresses and warms, discouraging cloud formation and precipitation. However, this descending air can also lead to the accumulation of airborne particles, such as dust, pollutants, and water vapor, in the lower atmosphere.

When these particles are brought down to lower levels, they can reduce visibility due to their density and concentration, especially in calm wind conditions that prevent dispersal. Consequently, the presence of these particles can create haze or fog, leading to poor visibility at low altitudes.

While particles can indeed be dispersed by strong winds or result from other mechanisms, in the context of high-pressure systems, the important factor is the effect of descending air bringing particles down from higher altitudes.