The sunset is appropriate. When her husband Karl XIII died in 1818, his dynasty passed with him and the Bernadotte family was brought in.
This is a high resolution image from Czech Wikipedia. Most versions of this portrait are blurred, probably to obscure cracked paint. High resolution can reveal spots and paint cracks as happened in this case. The flaws were fixed with Photoshop.
Charlotta appears to be wearing a partlet over a chemise, probably under thin straps that hold up her bodice in this 1814 portrait.
Keywords: 1814, von Breda, Queen Charlotte of Sweden, Hedwig von Schleswig-Holstein-Gottorf, Prinzessin Hedwig Elisabeth Charlotta von Schleswig-Holstein-Gottorf, Prinsesse Hedvig Elisabeth Charlotta af Slesvig-Holsten-Gottorp, Hedvig Elisabet Charlotta av Holstein-Gottorp, Hedvig, Elisabeth Charlotte of Holstein-Gottorp, Charlotta, prinsessa av Holstein-Gottorp, Herzogin von Södermanland, hertiginna av Södermanland, drottning av Sverige, drottning av Norge, Königin von Schweden und Norwegen, Queen of Sweden, Queen of Norway, Princess, Queen, Holstein-Gottorp family, curly coiffure, tiara, partlet, jewel décolletage, lace neckline ruff, chemise, modesty piece, vee décolletage, quarter length close virago sleeves, bodice, square neckline, strap sleeves, close skirt, robes