Answer:
cold, big, and blue are the adjectives
I think that absolute phrases are the underlined element in this passage by Charles Dickens.
The following ones can be identified: “… flowing up the river […] city”, “…rolling down the river […]city”. Absolute phrases happen when a noun and a participle (in this case the present participle –ing) function as an independent clause. In this case, they describe the clause, the manner of the movement of the fog.
