In old Testament times a pillar of cloud or smoke would sometimes appear over the tabernacle or temple (depending on which was in use) in order to indicate a special presence of God. Sometimes this appearance would communicate the pleasure of God (I Kings 8:11, ) but other times it would communicate His extreme displeasure (Numbers 12:5, 16:42). In the book of Revelations this cloud appears within the heavenly temple:
Then one of the four living creatures gave to the seven angels seven golden bowls filled with the wrath of God, who lives for ever and ever. 8 And the temple was filled with smoke from the glory of God and from his power, and no one could enter the temple until the seven plagues of the seven angels were completed.
I believe that this special display of God’s presence signifies how important these final judgments are to Him. He does this to show His extreme approval for the task of the specifically-chosen seven angels who are about to cast the last seven plagues onto the planet Earth. These angels are pictured as being given bowls that are “filled with the wrath of God.” The display of God’s presence is so extreme here, that “no one could enter the temple until the seven plagues of the seven angels were completed.” The time for judgment has come, and God is apparently making it His highest priority at this time.