"The previous bowls have been poured out upon the earth, the sea, the rivers and fountains, the sun, the throne of the beast, and the great river Euphrates. This, the last and greatest, is poured into the air; and immediately there is heard a voice out of the temple in heaven, proclaiming, "It is done!" What, then, is symbolized by the plague poured into the air? Of what is the "air" the emblem? In the Revelation the whole of nature is used as a great complex parable or symbol. What does the atmosphere especially signify? And the answer is not difficult. If earth, sea, rivers, fountains, the sun, a throne, etc., denote manifest spiritual realities, the air obviously would symbolize an invisible spiritual realm. And here we are helped by sundry hints of scripture usage."
Much more in the text:
"The ungodly movements of the world, be they social, entertainment, political, religious, educational, or otherwise, are the direct result of negative spirit influence transmitted to the masses through faithful ministers of unrighteousness who have become filled with the un-holy spirit, and consequently transmitters of the same, producing the supercharged atmosphere of sin and death. In this way Satan is indeed the "prince of the power of the air," meaning that he is the invisible ruler, which activity and authority he exercises in and through men -- "the spirit that now worketh in the children of disobedience!"