Actually, as a former jw, I can answer that very well. Witnesses believe that Jesus is Micheal, and they believe not about the upper atmosphere, but they believe He has returned invisibly.
They do not specify anything about the upper atmosphere, but that He is in heaven, and that His return was not seen by the human eye, but through eyes of faith. They claim that there are signs that point to His return, such as world war 1 when they
alledge the devil was cast down to earth having great anger knowing he has a short period of time, thus the outbreak of worldwar 1. They say that Christ had invisibly returned, and cast the devil down to the vicinity of the earth. The Bible clearly states that when Christ does return, every eye will see Him, so their reasoning is not logical. Regarding Jesus being Micheal, they use Daniel as proof in point. Saying that Micheal, the Prince of Peace is Jesus. Take a look towards the end of the book of Daniel, and there you will see why they claim Jesus is Micheal. They have also calculated a certain amount of time that has passed by as well as in Daniel, which points to the return of Christ invisibly. They have an estimated 2850 some odd days I believe, that they calculate “a day for a year, a day for a year” and point to the OT where it states that 1 day is as a thousand years to God. Meaning that they took this time period in the book of Daniel about 2850 some odd days, and added each day as a thousand years until Christ returned invisibly. It is all very confusing, but they have according to them, pin pointed the exact date that He returned, and that date came to about 1914, and therefore the devil was cast out upon Christ returning invisibly, and cast down to earth, and ww1 broke out as a result of the devil being cast down. The Bible clearly states in the NT about the return of Christ, that no man knows the hour or the day, not the Son nor even the angels know but only the Father who is in heaven knows the time and date that Christ will return. So there logic there if you can call it logic on their saying He is Micheal, and the time for the return is way off, and they have no proof He is Micheal, nor do they have proof He has returned “invisibly:”. Their logic is flawed. They contradict what Christ said about His return. Therefore they are a false belief as we all know. Here is a link from their site what they believe about the devil returning, and ww1, and part of it states about Christ being Micheal:
watchtower.org/library/dg/article_09.htm