12-hour clock - Wikipedia

Exeter Cathedral Astronomical Clock, showing the double-XII numbering scheme The natural day-and-night division of a calendar day forms the fundamental basis as to why each day is split into two cycles. Originally there were two cycles: one cycle which could be tracked by the position of the Sun (day), followed by one cycle which could be tracked by the Moon and stars (night). This eventually evol

[hidehara]

12:00am は 深夜ゼロ時のことなのね。12:00pm は noonと。12-hour 表記では 00時の概念がないのかぁ。知らなかった。

[tumo300-500]

知らなかったとはいえ、12AM, 12PM が納得いかない感じ。。

[minato128]

12時間表記

[burnercrew]

12時間表記と２４時間表記について