The ground is covered in snow.
The first snowfall of the year.
Sentence one says that the ground is covered in snow, it does not infer that it was the first snow fall of the year.
exists e1 x1 x2.(n_ground(x1) & in(e1,x2) & n_snow(x2) & Theme(e1,x1) & v_cover(e1))
exists s1 x1 x2.(n_year(x2) & n_snowfall(x1) & a_first(s1) & Theme(s1,x1) & a_topic(x1) & of(x1,x2))