Air was one of the four elements of classical Greek philosophy (the others were earth, fire, and water).
As such it is a complex symbol, and interpreting the meaning of air depends heavily on the larger context in the dream.
The classical element air symbolizes the intellect, ideas, creativity, communication, travel, and related matters. Thus, the state of the air (e.g., whether clear or foggy) may be a commentary on one’s ideas or communications.
[1]