Nebetah has seen the sky before, and the sea, both of which are visible in the environs of the winter palace. She's not going to gawk at being outdoors, no sir. She's being introduced to a man who's been to some distinctly plural number of continents, she can keep herself pulled together for the streets of Sothis and not embarrass his divine grace her brother or give the chaperone a hard time.
In the latest fashion of ludicrously rich eligible girls, Nebetah's wearing layers of light gauzy fabric, today in sea-green and amber, with enough embroidery on it to buy half a dozen normal people's houses; shoes of calfskin leather, tooled and dyed and stitched and perforated to the point of gaudiness; and not a speck of jewelry. Bare hands, unadorned ears, a sheer silk scarf over her head and around her neck that keeps the worst of the sun off but leaves it very clear that she isn't wearing a necklace. (She does own jewelry, but you don't wear it courting. Not when you could be taunting your date with how he could put jewelry on you and have you all to himself.)
The chaperone, great-aunt Maysoon, has Nebetah's clarinet stashed in her bag, in case the adventurer wants to hear her play. He probably won't, but just in case.