I'm thinking this is mostly funny...
as in "where'd you shoot 'im?" and the answer being "behind the davenport"
If you want to do a snow scene... effectivly?
you may want to paint the ground foam a color a lot like white.
otherwise and it looks a LOT liks a heavy layer of dust.
(which is what it is...)
so after the white paint, you want to have a little sparkly look.
at that point plaster as a dust and baking soda can have that look,
If you want to clean it because not-white dust settles on your winter...
you vacuum off the 'dusts' and reapply.
or...
you paint on irridescent medium and then you can wash or vacuum the scene.
I find winter tough, cause it is so clean.
spring is hard mecause of the many shades.
summer is easiest for the general green-ness
and fall has many shades again, just different shades.