Yes, those white trails are snow flacks caught in the act falling. This manhole cover with its lovely motifs of cloud, mountain and lily is the first I've seen with a name in English. That it is not covered with snow makes me think that all these covers are for the water system perhaps? Is there a competition for the town with the best man hole cover? Can this be called a grate if it doesn't have any grating holes? And what species are those mysterious lilies? The mysteries multiply.