Why should we use 世界で and not 世界に for 日本で一番高い山は富士山です


Why do we always use で in the following situations? 日本で一番寒い月は二月です。
日本で一番高い山は富士山です。 Why can`t we use use に here? There is no action in these
sentences yet we use で,rather we are indicating the place of existence.




I don't think this indicates a place of existence (February is not located in
Japan), but a limitation/focusing on the statement that follows: Considering
the weather in Japan, February is the coldest month. Out of mountains that are
in Japan, Mount Fuji is the tallest, etc.

This で can be used with non-location words:

チーターは陸上{りくじょう}の動物で一番速いです (Cheetahs are the fastest land animals)

家族で一番強い人は姉です (My sister is the strongest person in my family)

