The air is crystal clear. In winter, and during summer mornings, the air is often still. Tiny particles of smoke, dust, and sulfates accumulate, float in the air, and produce haze. During those windless, stagnant periods, we see a layer of haze obscuring the lower reaches of those mountains to the south. Tiny haze particles absorb and scatter sunlight.
Lighting is diminished, contrast is reduced, and colors are muted.
Folks that lived and visited in the Tahoe Basin between the 30s and 60s, swear that visibility was fantastic in those days. Sheep and cattle herders added more smoke by burning pastures to revitalize them for the following year. But, Native Americans used fire to manipulate their landscape, and that suggests a scene of smoky summer mornings instead of clear skies. When TRPA folks decided to set environmental thresholds for visibility in 1980, they needed a basis for the standards. Researchers M. Pitchford and D. Allison responded in May 1981, installed instruments in the Basin, and monitored visibility until June 1982.