I am eating a hot dog in a beautiful courtyard right around dusk, and I would like to exclaim in Latin, "How beautiful!"
I thought of saying "Quam pulchra!" which can't be far off, but I am wondering whether there is a better choice. For example, would miranda be better? Would any other words be better?
I look forward to your feedback, so that on similar twilit evenings I can exclaim this without hesitation.
Use the superlative of any appropriate adjective: iucundissima, suavissima, , dulcissima or, especially in those circumstances, amoenissima. It gives more of the emphasis that you seem to be looking for. You might avoid the ellipse with Tempestas, quam amoenissima! or something similar.
For what it's worth quam pulchra is attested in a Post-Classical context (Vulgate:)
Quam pulchra es et quam decora, carissima, in deliciis! (Can 7, 7)
Perseus treats quam as too common a word (a stop word, excluded from searches,) so it is difficult to look for the whole phrase. I found by chance an example of tam pulchra that is attested classically:
quid ais, Eruci? tot praedia, tam pulchra, tam fructuosa (Cic. S. Rosc. 15, 43)
... and also examples of quam + adverb (unfortunately no adjectives so far) as an exclamation. Prominently:
quam multa quam paucis! (how much [you have said] in a few [words], from a letter by Cicero to D. Brutus)
