I didn't learn how to use the 3 ways of saying there in Portuguese until I had been living in Brazil more than a year. That changed suddenly when talking on the phone I said, Como vai lá?... followed by : silence on the other end. It was as if I had said, Como vai lá em Londres?.
Oh! Você quer dizer, Como vai aqui? Bem... Estou bem!
That was the eventual response. If you ask a Brazilian OVER THE TELEPHONE how it's going lá. It doesn't really compute. It's like you are asking them how it's going in some other place far, far away. Aí is the hardest there to get - here is the rule -- you'll have to struggle to make sense of it.
aí: where the listener is.
So for example, asking someone on the other end of the line about there, you have to use aí:
Or they could be in the same room:
They could even be right next to:
Brazilian's say Hey there! like this: E aí! Literally: And there! They always use aí because the there is always right where the listener is.
Making my head spin already, though I know this stuff de coração.
ali: there within eyesight
Anything that's within eyeshot is ali. Pointing out a restaurant on the other side of the street is ali.
lá: out of sight
This is the there that you probably already know. You can use this as there in all cases by default, but you are letting people know that you're just a beginner. When you start to use ali and especially aí, you're on your way to fluency in the language.
*This last one just goes to show you that even Brazilians blur the line between lá and ali. They will often use lá even for things within seeing distance (Lá vem ela = Here she comes).
More good examples of how lá is really used in Portuguese.
Saying there in Portuguese
E aí in action: