Meanings of appears dark in English

The mirror now reflects nothing into the other closet; it simply appears dark.

Series were now given to test the assumption that red appears dark to the dancer.

And the domestic future appears dark.

But right at the centre of the iris lies the pupil, the hole that lets light in, and that appears dark.

The angry eye of the hurricane-like storm appears dark red while the fast-moving hexagonal jet stream framing it is a yellowish green.

The neat material has a modulated B4 phase, which appears dark under crossed polarizers and shows no observable optical rotation under decrossed polarizers.