In "The Rime of the Ancient Mariner," why is the Sun called "glorious" in line 97 and yet called "bloody" in line 111?

In line 97 the sun is called glorious for a couple of
reasons. Their ship was surrounded by fog and mist, and once the sun rose, the fog and
mist cleared away.  The sun was described as glorious because it helped to clear the
haze so they could sail on.  This word also has religious reference to it.  It was as if
it took something more powerful than humans or nature to get them out of
trouble.

In line 111 the sun is described as bloody because
of the new situation they are in.  They are not happy. They are all stuck at sea with no
winds, no food or water. The sun simply beats down on them, dehydrating them even more. 
The sun is called bloody because it is drying them up and beating down on them
violently.

The author uses the power of nature along with
characters in order to further explain the themes of the poem.  The sun is one of the
most powerful aspects of nature that we have today, and Coleridge with his love of
nature uses the sun to help portray the emotions and trials of the mariner.  Depending
on the situation, the sun could be beautiful and helpful, or it could be cruel and
debilitating.