The figure of speech the author is using is SIMILE.
Simile is a figure of speech that is used to make comparison between two things that are of different kinds in order to make a description more emphatic. Simile can be easily identified in sentences because it usually have the words 'as' and 'like' attach to it. For instance, this sentence is a simile: Daniel is as brave as a lion. The sentence is comparing a human being [Daniel] to a lion [an animal]; these are two unlike things, but the two have bravery in common.