What imagery is there in the myth Persephone (and Demeter)?Please can you include if it creates an atmosphere too?

Because you don't mention which specific text you are
reading to learn the myth of Persephone and Demeter I am not sure what specific imagery
that author is using to tell the story.  That said, the story of Persephone and Demeter
is the story of why the seasons change, so there may be language that appeals to any or
all of the senses that relates to that.  Also, Persephone travels to Hades and while
there eats the pomegranate seeds, so there may be imagery related to that place and that
piece of fruit.

The myth says that Persephone was kidnapped
by Hades, the god of the underworld).  She would have been allowed to return to earth if
she did not consume anything when she was there, but she was presented with a beautiful
pomegranate and couldn't resist its juicy seeds, so she ate them and was therefore
condemned to stay in Hades forever.  Persephone's mother, Demeter was the goddess of the
harvest.  Because she was so saddened over the loss of her daughter she turned the
weather weather cold and no crops grew.  Realizing that this was going to destroy
mankind, the gods intervened and made a compromise:  Persephone would return to the
earth for half of the year and would spend that other half in the underworld.  Demeter
agreed.  Hence, Demeter brings warmth and growth to the earth in the spring and summer
when Persephone is with her, and ends the growing season with colder weather in the fall
and winter.  In a written version of the story you should look for images of the various
seasons or change in seasons, for images of the scary, dreary atmosphere on earth in the
winter and of the underworld at all times, and of the temptation of the pomegranate
fruit.  I  would assume that if you are being asked about atmosphere that the imagery
does, in fact, create the positive or negative atmosphere of those places and those
times of year.