YES....I just made my 1st Portuguese Joke!!!!
I am the greatest!
I was just discussing this with a Brazilian language partner and this is how he explained it to me:
aí = over there near you
ali = over there away from both of us, but we can both see it, or over there away from me, but I can still see it
là = over there (in a location in another room or maybe even in another country/ we can't see the location or as Zumak said "something that is so far that it cannot be readily seen"
Yes, they are synonyms, but, as this wonderful article explains, «ali» (no accent since the stress naturally falls on any «i» at the end of a word) indicates something that is of closer proximity and perhaps still visible, whereas «lá» (acute accent on the «a») indicates something that is so far that it cannot be readily seen: https://ciberduvidas.iscte-iul.pt/consultorio/perguntas/o-emprego-dos-adverbios-de-lugar-aqui-ai-e-ali-ou-ca-e-la/24985.