According to New York, Niu's sky painting works are reminiscent of Chinese calligraphy; of his "longing for the sky while he was in jail"; of chalkboard drawings from his childhood (because paper was too expensive); "and of the Tibetan belief that the souls of saints become smoke and cloud shapes as they leave the body."
這件作品具有多重象徵意義：讓人想起中國書法；牛波對天空的嚮往；牛波童年時代的大陸小孩，他們只能用粉筆在黑板上畫畫，因為紙太貴：以及西藏密宗相信聖者死後靈魂離開身體，就會化為雲煙。