Final answer:
CR artifact fog in the natural setting like San Francisco Bay is caused by warm and cold air colliding, while at a Rolling Stones concert, the fog is artificially produced to set a mood.
Step-by-step explanation:
When a CR artifact such as fog appears, it can be attributed to different causes based on the context. In a natural environment, like over San Francisco Bay, fog is caused by the collision of warm and cold air masses. This is a prevalent meteorological phenomenon that can significantly reduce visibility.
In contrast, at events such as a Rolling Stones concert, fog or smoke used onstage is artificially generated through machines. This type of fog is created to establish a specific mood or association for the audience, and it is purely symbolic. It adds to the aesthetic and experience of the performance without any meteorological implication.