The words עשן (smoke) and ענן (cloud): עשן andקיטור (smoke) come from boiling rain, while ענן is a special name for vapor that goes up and comes together as one (when it is scattered, it is called ערפל - fog). And these words are borrowed for the theme of incense when there is an herb going up as smoke and for the cloud that is created during the time when the Presence of Glory is revealed.