What is the imagery of sight and sound in "To Build a Fire" by Jack London?

From the very beginning of the story, imagery is used
(like many of London's stories) to convey the feeling of the place and at times to also
foreshadow events to come.  In the first paragraph, London
writes:

There
was no sun nor hint of sun, though there was not a cloud in the sky. It was a clear day,
and yet there seemed an intangible pall over the face of things, a subtle gloom that
made the day dark, and that was due to the absence of
sun.

The fact that this
absence of sun does not concern our intrepid traveler is a clue as to what will happen
to him down the trail.  It also helps to build the idea that this "intangible pall" will
likely bring about some future tragedy that no one can quite put a finger on yet, but
will become clear.

London uses images like this throughout
the story.