Cold front through Baja California. Winds are related pressure differences - high to low. Air coming from region of higher elevation. Air comes from Reno, gets compressed because it descends. California is totally clear, and ground is dark.
Relative humidity is lower.
When clouds are brighter and whiter in picture, they are thicker and colder at the tops. The chart runs through 24-hour period. When sun goes down, air pressure decreases. Downslope winds that flow outward from a region of dynamically-induced surface high pressure located over a region of elevated topography. During warmer season the pressure is lower in the interior and higher along the coast.