Park rangers and firefighters were burning various parts of the valley during the weekdays. This made the air in the valley difficult to breathe during the afternoons, but this was mitigated by the really cool sunset effects caused by the smoke. In the above image, the sun is setting behind Lower Brother; Sentinel Rock, Taft Point, and Cathedral Rocks are shrouded in the smoke on the left.
Current Park Service doctrine is a direct reversal of the past practices of putting out fires as soon as they are noticed. Now, rangers will allow naturally starting fires (such as lightning fires) to burn as long as humans are not put in danger, and will start controlled burns during the autumn months. This not only reduces the amount of tinder that can fuel monster fires, but also removes scrub growth that prevents native trees from germinating and growing.
