How does the weather in the graveyard scene in ch. 29 contribute to the mood? The Adventures of Huckleberry Finn by Mark Twain

As tensions mount in Chapter 29 The Adventures
of Huckleberry Finn, the king and the duke find themselves falsely defending
their claim to being brothers of the deceased Peter Wilkes now that his real brothers
Harvey and William have arrived.  After a time, a "husky" speaks up, contending that he
has observed the king at a place in the morning. After listening some, a doctor in the
crowd enters the interrogation because he believes that the king and duke are frauds. 
He suggests that if they are not frauds, they should not object to someone sending for
the inheritance and letting it be kept until they are proven to be the rightful
heirs.

Quickly fabricating, the king explains that the gold
has been stolen by the slaves. But, when Huck is asked if he saw the slaves stealing, he
replies that he thought they were hurrying out of the room because they did not wish to
awaken his master.  At this point, a lawyer demands that the king and the duke and Mr.
Harvey Wilkes write on a piece of paper in order to compare the handwriting to
letters of Peter Wilkes from his brothers; however, none match.  Mr. Wilkes says that
his brother William writes for him, but now his arm is broken.  Remembering a tattoo
on Peter, Mr. Wilkes asks the king to identify what was tattooed on his brother's
chest.  However, no one can verify or deny the king's answer since no one observed
anything.  So, the decision is made to exhume the body.

At
this point, with great tension in the air, a storm brews.  As everyone "swarmed along
down the river road, just carrying on like wildcats," the sky darkens and lightning
begins to flash, creating a truly gothic atmosphere to the scene.  The wind begins "to
shiver amongst the leaves" just as Huck shakes nervously since his emotions are as
tumultous as the weather. He narrates, 

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everything was going so different from what I had
allowed for...there was nothing in the world betweixt me and sudden death but just them
tatoo-marks.  If they didn't find
them--

Without lanterns the
gravediggers can only work in the flashes of lightning which certainly lend an even more
eerie atmosphere to their activity.  To add to their uneasiness, the thunder booms, in
the strobe-light of the sky the shovelfuls of dirt come "sailing up out of the grave"
only to be obliterated by the darkness in which nothing is visible.  Just as the men
pull the coffin out of the grave and unscrew the lid, and men crowd and shove one
another to see,

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the lightning let go a perfect sluice of white
glare, and somebody sings out:

"By the living jingo, here's
the bag of gold on his
breast!"

At this point, Huck
frantically flees down the dark road that fortuitously hides him.  And, because of the
storm, people in the town are not outside.  Just as Huck "sails" by,
"flash comes the light" in Mary Jane's house, But, in an instant,
it is dark, and Huck loses hope.  Having run out of town, Huck searches for a boat "to
borrow" and the lightning again reveals what he needs.  When he reaches Jim with the
skiff, the lightning shines on the man and Huck is frightened as he looks like "old King
Lear and a drowned Arab all in one."  But, Jim rescues Huck who has fallen overboard in
his fright, trying to hug and kiss Huck because he is so happy to see the
boy.

Clearly, the disturbing thunder, the ghostly glare of
the lightning, and the frightening darkness of the storm demonstrate the sympathy of
nature with Huck's feelings.