茫 rarely stands alone. You'll meet it in 茫茫 (vast and boundless), 茫然 (at a loss / blank), 渺茫 (distant and uncertain), 迷茫 (confused / hazy). Pick the compound; 茫 alone is poetic.
memory
Top half is 艹 (grass radical) over 亡 (perish, but here phonetic 'mang'). Imagine grass stretching out so far it 'perishes' on the horizon — that's 茫.
