When to use 座る vs 坐る


As I'm starting to explore more kanji, I've come across these two ways of
writing すわる (to sit): 座る and 坐る.

I would like to know when to use one over the other. Are there nuances that
would make one very inappropriate to use in a special setting? Is one being
used for sitting with a roof over one's head (a house) vs under open sky (on a
bench in a park)?




To built up a bit on my comment ( _坐 is old school 座. Now, you might only see
the former in books and museums (it's quite common to see 坐像{ざぞう}). May be
there are nuances but I never heard of._ ) 語源-allguide has an entry on 座る.

> 【意味】 座るとは、膝を折り曲げて腰を下ろす。ある地位や役に就く。
>
> 【座るの語源・由来】  
>  座るは、落ち着いて動かないことを表す「据わる（すわる）」と同源。  
>  「居ても立ってもいられない」と言うように、古く、「立つ」の対義語は「居る」であった。
> 平安時代末頃から、「居る」が「存在する」といった意味で多く用いられるようになったことから、他動詞「すう（据う）」が自動詞化した「すわる」が、「立つ」の対義語として用いられるようになった。  
>  漢字の「坐」は「人＋人＋土」で、地面に尻をつけることを示している。  
>  「座」の漢字は、「广（いえ）＋坐」で、家の中で人が座る場所のことである。  
>  「坐」が動詞、「座」が名詞として用いられたが、常用漢字では「座」に統一された。

Translation:

> 座る means _bend your knees and seat your rear_. Or, be employed at a
> position.
>
> [Etymology of 座る]  
>  座る shares its etymology with 据｛す｝わる and means _being calm without moving_.  
>  As seen in
> [「居｛い｝ても立ってもいられない」](https://kotobank.jp/word/%E5%B1%85%E3%81%A6%E3%82%82%E7%AB%8B%E3%81%A3%E3%81%A6%E3%82%82%E5%B1%85%E3%82%89%E3%82%8C%E3%81%AA%E3%81%84-436527)(boils
> at the core but can't afford not keeping calm), the antonym of 立つ was 居る.  
>  Since, by the end of the Heian era, 居る became used a lot in the meaning of
> _to exist_ the transitive verb 据｛す｝う turned into the intransitive verb
> 据｛す｝わる and (すわる) started to be used as the antonym of 立つ.  
>  The kanji 坐 is made of 人＋人＋土 and means to seat one's rear on the ground (as
> you have guessed in your question).  
>  The kanji 座 is made of 广（いえ）＋坐 and refers to a place where one would seat
> in a house. 坐 was used as a verb, whereas 座 was used as a noun. But this 坐
> is not a 常用漢字, 座 is now used for both.




坐る is very rarely used. I have seen it little.

As far as I searched, 坐る was a Kanji for a verb, and 座 was a Kanji for a noun
that means a place to sit in early Showa era.  
Though the government enacted the following rules in Showa 31th(1956).
<http://kokugo.bunka.go.jp/kokugo_nihongo/joho/kakuki/03/pdf/doon.pdf>  
× 坐→座

It seems that they were unified into one Kanji by this rules. That is to say,
坐 is old Kanji.

