Appear, loom and emerge all mean to come out into view. In use, however, they are only rarely interchangeable.
Appear is weakest in its implication of a definite physical background or a source; consequently it sometimes means merely to become visible or to become apparent (see EVIDENT).
- one by one the stars appeared in the sky
- nothing appears in the testimony to cause doubt of the defendant’s guilt
Sometimes it means to present oneself in public in a particular capacity or to be presented or given out to the public.
- Clarence Darrow appeared as counsel for the defendant
- Booth appeared nightly as Hamlet for the last two weeks of his run
- the new biography of Lincoln will appear next month
- weeklies usually appear on Thursday or Friday
Loom means appearing as through a mist or haze.
- a smear o f . . . lead-colored paint had been laid on to obliterate Henchard’s name, though its letters dimly loomed through like ships in a fog
—Hardy - between the bed and the ottoman . . . the cot loomed in the shadows
—Bennett
Because things seen in a fog are often magnified by their indistinct outlines, loom, especially when followed in figurative use by large or great or when followed by up, suggests apparent and sometimes appalling magnitude.
- some mornings it [a mesa] would loom up above the dark river like a blazing volcanic mountain
—Cather - that which loomed immense to fancy low before my reason lies
—Browning
Emerge definitely implies a coming out into the open from something that envelops: the word therefore presupposes a period or condition of concealment, obscurity, gestation, or insignificance
- the sun emerged from the clouds
- after a long hunt for him, we saw him emerging from the crowd
- that part of northern Ohio where the Bentley farms lay had begun to emerge from pioneer life
—Anderson - Lord Sligo emerges from this account as an able and conscientious administrator
—Times Lit. Sup.