12-hour clock / 24-hour clock

There are two expressing ways of the time: 12-hour and 24-hour. The former is regarding a day as "2 times 12 hours", and the latter is just "24 hours". Let's see the features of each expression.


*12-hour*
This is popularly used in conversations. I think it because the less syllable is used compared with the 24-hour expression, in short, this way is easier to say. But confusion could be exist. For example, we have no way to know what "2 o'clock" means; in other words, we can't know whether it means "2 o'clock in night" or "2 o'clock in daytime". To avoid confusion, we use "a.m." or "p.m.". The former means "from 12 o'clock in night to 12o'clock in daytime" and the latter means "from 12o'clock in daytime to 12 o'clock in night". 


*24-hour*
This is popularly used in business. For example, the time tables of trains, buses,TV programs, business hour of a shop, and so on. We don't mistake "2 o'clock in daytime" for "2 o'clock in night" as we express it as "14:00". However, it is strange that we see information like "24:30~27:00". The writer just emphasize that it is MIDNIGHT though. And, some people feel difficulty to distinguish "17:00" from "7:00 p.m." as they are similar.


By the way, I found a fantastic clock!

It seems that it shows 10:10, but it shows 20:10 actually. This clock expresses 24 hours by one round :) I've never seen 24-hour analog clock!!