Ante- meaning “before”, meridium meaning “highest point of the sun” as in when the sun crosses the “meridian” which would be the line in which it is now setting instead of rising.
Passing from post-meridian to ante-meridian is exactly 12 hours from when the sun passed the meridian point, to keep it “consistent”.
I get though that it’s confusing, I questioned it a lot as a young boy.
Personally I believe that is stupid that we go from 11pm to 12am, but the reason is that the cutover is “12”, and everything after 12 (including the hour) are considered morning.
Like others have mentioned, we should really be using 24hr time these days where possible. Additionally I’m of the impression that we should use ISO8601 for date formats instead of what the Uk does (or even worse: what the US does).
I'm propagating the ISO date format with Guerilla tactics. Whenever I come across meeting minutes or documentation pages using a different date format, I silently reformat into ISO date format and then it just catches on. The "normative force of the factual" can be strong.
FWIW there are very few moments in time and space where the sun will have reached its highest point at exactly 12:00 PM so even that logic is nonsensical. The only consistent mental model is that for traditional reasons clocks go from 1 to 12 and 12 is actually the zero point of the next 12 hour cycle. It's literally just a cultural artefact you have to commit to rote memorization because there's no good reason for it to be that way ever since digital watches became a thing and people no longer had to rely on bell towers to give them the time of day (which can't strike zero times for obvious reasons).
The 12 hour cycle is fine. The problem is that it starts at 12 and then rolls over to 1, rather than starting at zero. You can have a duodecimal system without starting at 12.
It's ante meridiem and post meridiem. Let me explain.
"dies" is the Latin word for day. It is in the e-declension. Not many words in Latin have the e-declension. Another one is "res", the Latin word for thing.
I don't know a lot about "meri", but it seems that "meridies" is also in the e-declension.
"ante" and "post" are prepositions which ask for the accusative. The accusative is mostly lost in English, but often when you say "me", it's accusative. If you say "after I" it feels wrong. You say "after me". German has preserved the accusative, so it is natural for me.
Now, in the e-declension the ending for the accusative is "-em". So you say ante meridiem and post meridiem.
Ante- meaning “before”, meridium meaning “highest point of the sun” as in when the sun crosses the “meridian” which would be the line in which it is now setting instead of rising.
Passing from post-meridian to ante-meridian is exactly 12 hours from when the sun passed the meridian point, to keep it “consistent”.
I get though that it’s confusing, I questioned it a lot as a young boy.
Personally I believe that is stupid that we go from 11pm to 12am, but the reason is that the cutover is “12”, and everything after 12 (including the hour) are considered morning.
Like others have mentioned, we should really be using 24hr time these days where possible. Additionally I’m of the impression that we should use ISO8601 for date formats instead of what the Uk does (or even worse: what the US does).