ייִדישער מחשבֿה אויף דברים 31:15

And the clouds of glory were by that agency of Aaron: We have already told you that the connection of the Holy One, blessed be He, with Israel was through Aaron. It is in the same way that you find in every place that the Divine Presence was revealed among the lower beings, it was with the clouds of glory - "And the Lord appeared [...] in the pillar of cloud" (Deuteronomy 31:15), and such was always [the case]; "It was on the third day, in the morning, that there was thunder and lightning; a heavy cloud" (Exodus 19:17). And likewise, in every place where there was the revelation of His Divine Presence to the lower creatures, it was with the pillar of cloud. And that is why it was fitting that it be by the agency of Aaron, for the connection between God, may He be blessed, and Israel was through Aaron, as was explained.