[Grammar] "where" or "in which"

[gchman]

Hello there.

(A) They used to live where the weather is very nice.
(B) They used to live in which the weather is very nice.

I wonder if both sentences are correct.
My teacher said "in which" is wrong.
I would like to know why "where" cannot be replaced with "in which".

Anybody who could explain this please help me.

[abaka]

The word "which" is used only as a pronoun. What does it refer to here?

"Where", on the other hand, can be and is used more loosely (without antecedent, as a correlative or interrogative adverb, if you need the grammar).

The two are not equivalent. "Where" can replace "in which" more often than "in which" can replace "where".

You live IN a house, city, country, or the world. You live AT a place. If you use "in" or "at" "which", you have to mention these explicitly (as antecedents).

The house in which they lived had good air conditioning.
The house they lived at had good air conditioning.
The house where they lived had good air conditioning.

The place at which/where they lived had nice weather.
The place they lived at had nice weather.
The place where they lived had nice weather.

"They used to live in/at which the weather was very nice." POOR

They used to live where the weather was very nice.

[gchman]

Now I understand.
Thank you very much, Abaka.