Why does Buck feel ashamed at the end of chapter 1, during his first snow?

Buck, coming from California, had never experienced snow before. He tastes it and id disappears in his mouth. The men are laughing at Buck's response to snow.

More of this white stuff was falling through the air. He shook himself, but more of it fell upon him. He sniffed it curiously, then licked some up on his tongue. It bit like fire, and the next instant was gone. This puzzled him. He tried it again, with the same results. The onlookers laughed uproariously, and he felt ashamed, he knew not why, for it was his first snow.