The author compares his grandmother to a winter landscape to paint a vivid picture of her physical appearance and the emotions she evokes in him. Here are the details:

Physical Appearance:
- The author describes his grandmother's hair as "white as snow," which is a common metaphor used to describe hair that has turned grey or white due to aging.
- He also mentions her "wrinkled face," which could be compared to the creases and lines that form on the surface of the earth during winter.

Emotions:
- Winter landscapes are often associated with feelings of coldness, stillness, and even loneliness. By comparing his grandmother to a winter landscape, the author is conveying a sense of sadness or melancholy.
- He also uses the phrase "silent as the snow," which further emphasizes the idea of stillness and quietness. This could suggest that his grandmother is reserved or introverted.

Overall, the comparison to a winter landscape helps to create a powerful image of the author's grandmother and the emotions she brings up in him.