Fallen Snow

It isn’t right when snow, once white, Turns dirty brown or grayish For when we glance, we’ll look askance And maybe feel dismayish. It’s very strange. What makes it change? My grandson asked, in wonder. Well, cars and feet out on the street Make all the white go under. Some parts stay clean and quite pristine Just like a new marshmallow, But walk around, if on the ground, You see some snow that’s yellow!