Which condition is denser-than-air effects most significant?

Denser-than-air effects are most significant under conditions of lower wind speeds. When wind speeds are low, the atmosphere tends to be more stable, which allows heavier gases to accumulate in low-lying areas rather than dispersing quickly. This stability can lead to more pronounced effects from denser-than-air materials, as they do not have the dynamic force of wind to aid in their dispersion.

In contrast, higher wind speeds generate turbulence, which helps mix the heavier gases with the surrounding air, reducing their concentration in any one area and helping to disperse them more rapidly. Higher temperatures can also contribute to the tendency of gases to rise, which decreases the significance of denser-than-air effects. Finally, lower release rates may not provide enough material to create significant pooling or concentration of denser gas, so conditions that minimize these release rates are less impactful. Thus, lower wind speeds create the ideal environment for denser-than-air effects to be observed more significantly.