咪蒙杀气腾腾:what is white and comes down from the sky in winter

What is clean when it is black and dirty when it is white? What is black when it is clean and white when it is dirty? What is black when it is clean and white when it is dirty? Riddles(What is black when it is clean and white when it is dirty?) What is black when it isclean and white when it is dirty? What is black when it`s chean and white when it`s dirty? what is white and comes down from the sky in winter what is the difference between decoration and ornament?say decoration(or ornament) engineering co. Rideeles It is cold and white . What’s black and white and read all over?