white
皚 centers on a pure, brilliant white, often describing snow or frost. It is a single-concept color kanji without major distinct senses.
皚 combines 白 (white) with 豈, which likely contributes the sound. The character is used for a pure, snowy white.
The left side 白 means white, and the right side 豈 looks like a piled-up shape. Picture a heap of pure white snow: 皚 is that brilliant white.
For ガイ, imagine a guy standing in a field of pure white snow: guy -> ガイ, and the snow is 皚 white.