"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:
"There is, of course, an individual and personal application as the Babylon within each of us is judged. The mighty earthquakes come to each individual as the Lord shakes each believer from the death-hold of the spirit of Babylon, to be loosed unto the complete control and Lordship of Jesus Christ through the indwelling Spirit. All the cities (the religious strongholds, dominating hierarchies, denominational headquarters) of the nations fall. They fall within the affections of each of us! They all fall before the greater revelation of Jesus Christ! Every island of religious gatherings flees away. Every mountain of religious achievement, fame, and power crumbles and are no more. The ultimate truth of God's great hail falls unrelentingly upon every thought, concept, doctrine, and tradition of man, crushing it into the earth. The spirit of Babylon is marked "finished" because the Lord, by His Spirit and His Word, puts down all rule, authority, and power! Isn't it wonderful!"