Normally, the ground is covered in detail including grass, leaves, sticks, stones, etc. and that detail is generally on the dark side of brightness. When it snows, those details are covered over and the ground becomes a smooth bright white palette mostly void of detail except possibly an even snow texture. As all kids know so well, what a blank white palette needs is something on it.
Shadows are a great option for that something. Especially helpful in this pursuit is that winter brings a low angle sun that casts long shadows even at mid-day. Additionally helpful is that the deciduous trees are bare in the winter and cast clean shadow lines (instead of complete shadows from a leaf canopy).
While trees cast great shadows, there are plenty of other options. Look for shadows beside fences (as shown in this example). Make your own shadows using your body (for a shadow selfie) or anything else your creativity can come up with.
This winter, if you are fortunate enough to live or travel to a location where there is snow on the ground, take advantage of that blank white palette. And remember, the clock is ticking after a snow storm. Fresher is better in the case of snow.