Fill factor (density times duration) determines whether a granular cloud is sparse, covered, or packed

The fill factor of a granular cloud is the product of grain density (grains per second) and grain duration in seconds. A fill factor below 1 means the cloud is sparse: gaps of silence exist between grains, producing a pointillist, staccato texture. A fill factor of approximately 1 means the cloud is covered: grains end just as the next begins, producing continuous texture without excess overlap. A fill factor above 1 means the cloud is packed: grains overlap, increasing amplitude and producing a richer, denser texture due to superposition. The fill factor is the primary parameter controlling the opacity and character of a granular texture, independent of the individual grain properties.

Examples

Density=10 grains/sec, duration=20ms: fill factor = 0.2 (sparse, gappy). Density=50 grains/sec, duration=20ms: fill factor = 1.0 (seamless coverage). Density=100 grains/sec, duration=20ms: fill factor = 2.0 (overlapping, dense).

Assessment

Calculate the fill factor for a cloud with 80 grains/sec and 15ms grain duration. Is this cloud sparse, covered, or packed? What texture character would you expect?