It is unusual and probably used infrequently, but it would be considered modern and correct to use it, even if perhaps a bit technical. There is another word which means the opposite which is just as fun. We won’t get to that (if ever) for years and years though. And it’s our first geographical word.
adret
Geogr.
A (mountain) slope which faces the sun. Cf. UBAC.
Neh 