Today’s Photo of the Day is a beautiful sunset shot from the NPS Air Quality cam that looks west from Turtleback Dome (just above the Wawona Tunnel).
What you’re seeing is smoke from the Grouse fire sinking into the Merced Canyon. In the far distance what looks like clouds is actually smog over the Central Valley. Ozone layers within the park are still low and in the good range but Particulate Matter is in the moderate range, sometimes climbing into the Unhealthy for Sensitive Groups.
For more information on the Grouse Fire and other fires burning within the park you can check out: http://www.nps.gov/yose/parkmgmt/current_fire.htm