I've talked before about the difficulty of communicating the often enormous scale of nature, mountains compressed into an image often lose their grandiose sense of scale--a topic I devote an entire section to in my upcoming book on photo composition.
This image seems to work, I can identify at least three ideas that help communicate scale. The contrast between the sharp burnt trees foreground and the soft, mist-covered mountain cues distance and scale. The snow-caps on the mountain also provide a hint. Finally, the scale of the lake on the right helps us to read the scale of the lake, and (by comparison) the mountain. It's not enough to hope that a large object will 'feel" large in an image, it's important instead to think about the sorts of signals we can use to help our viewers "read' the intent of our images more clearly.