Re: the Ascension, Jesus was fulfilling a lot of important Bible verses that way, as well as showing once again that He was Master of all the universe.
Re: the clouds, there’s a fair amount of Biblical and poetic association between thick dark or thick white clouds in the sky and the bright shekhinah glory around the Tabernacle. Clouds don’t just represent mystery symbolically; they really do hide things from sight, if you’re on the ground!
Clouds also are kind of two-sided. They contain rain and they shade the ground, which is good and hopeful. But they also can herald dangerous storms and winds, flash floods, crop-destroying hail, and even snow.
It kills me, how people tend to belitte the Bible’s use of nature symbolism, and to disregard any event that uses it as of course not true. But in everyday life, even atheist people are happy to see a rainbow; and even animals respond to the moods of the weather with changes in their own moods.
So of course it’s silly to say that Jesus “could not” come back, under certain weather conditions. It’s equally silly to think that He couldn’t or wouldn’t produce weather on a dime, to fit whatever effect He wanted. (Or, if you like, that He couldn’t arrange things from the beginning of time to make sure that things just happened the way He wanted them to.)
If you were God, and had power to do all things, why would you not make sure that the stage setting was always appropriate? If human speakers and actors can arrange things to affect their audience psychologically, why would they be more diligent about it than God?