Azkaban
Sirius tells Harry about the conditions he endured inside the Azkaban prison. He tells him that any prisoner in there would go mad, and some of them eventually stop eating. Any prisoner there, according to Sirius, could easily lose their will to live. The prisoners know that the end is near for them when the Dementors start flying above their cell, excited to be able to feed off of their pain and misery. The imagery Sirius offers of the prison is bleak and depressing.
The Corpse of Cedric Diggory
The description of Cedric’s corpse, "his open gray eyes, blank and expressionless as the windows of a deserted house" (258), in the backdrop of Little Hangleton's graveyard with the old Riddle mansion in the distance, present an overwhelmingly sinister and bleak landscape. Imagery like this contributes to the overall bleaker tone of The Goblet of Fire compared to previous installments.
The World Cup
Rowling describes the campsite at the Quidditch World Cup, where witches and wizards from across the globe convene:
Here and there adult wizards and witches were emerging from their tents and starting to cook breakfast. Some, with furtive looks around them, conjured fires with their wands; others were striking matches with dubious looks on their faces, as though sure this couldn’t work. Three African wizards sat in serious conversation, all of them wearing long white robes and roasting what looked like a rabbit on a bright purple fire, while a group of middle-aged American witches sat gossiping happily beneath a spangled banner stretched between their tents that read: THE SALEM WITCHES’ INSTITUTE. Harry caught snatches of conversation in strange languages from the inside of tents they passed, and though he couldn’t understand a word, the tone of every single voice was excited. (32-33)
The imagery here, lively and celebratory, demonstrates the diversity and general sense of harmony enjoyed among wizards in Rowling's universe.
The Leaving Feast
Rowling describes the "Leaving Feast," the last feast before summer, that occurs every year. But this year, after the Triwizard Tournament, it's very different. She writes, "When he, Ron, and Hermione entered the Hall, they saw at once that the usual decorations were missing. The Great Hall was normally decorated with the winning House’s colors for the Leaving Feast. Tonight, however, there were black drapes on the wall behind the teachers’ table. Harry knew instantly that they were there as a mark of respect to Cedric" (291). This is another bleak image that directly juxtaposes familiar images from previous installments of the series, i.e. the usual celebratory nature of the Leaving Feast, and it reinforces the sense of imminent darkness and struggle that awaits in a world where Voldemort once again reigns supreme over evil-doers.
