The atmosphere of Uranus, like those of the larger gas giants, Jupiter and Saturn, is composed primarily of hydrogen and helium.At depth it is significantly enriched in volatiles (dubbed ices) such as water, ammonia and methane.he opposite is true for the upper atmosphere, which contains very few gases heavier than hydrogen and helium due to its low temperature. Uranus's atmosphere is the coldest of all the planets, with its temperature reaching as low as 49 K.