This is what I was taught at school too. We were told that to use either AM or PM after the figures 12.00 was a logical absurdity and always to say 12.00 noon or 12.00 midnight.
(adding A.M. or P.M. to 12:00, I will note, is a big pet peeve of mine. Sticks in my craw along with the apostrophe in the possessive pronoun “its.” I’ve almost given up explaining it, but I still grimace whenever I hear or read “12:00pm”)
There is a 12:00 Noon (or just Noon) and a 12:00 Midnight (or just Midnight), There is no such thing as a “12:00 AM” or “12:00 PM”.
Also, in universal standard time, the hour between 12 midnight and 1 AM is 0000 hours. It is NOT 2400 hours. We have a 24 hour clock here at work that reads “12” and “24” at the top. Wrong, wrong, wrong. That should read “12” and “00”.
Yes, I know, people have their conventions and commonly refer to noon as either 12 PM or 12 AM (depending on which sort of silly-person they prefer to be). But people also routinely say: “I could care less” when they mean the exact opposite. Just because a lot of people do something doesn’t make it correct.
Here’s the reason: 1201 to 1259 is definitely after noon, and 0001 to 0059 hours is definitely before noon. So we call noon “12:00 PM” so that it will have the same suffix as the minutes in the hour immediately following it, and likewise for midnight.
And we could use the same reasoning to show why Noon should be called 12:00 AM.
If everyone was at least consistent I wouldn’t carp on about “It’s not am or pm, it’s just noon” but until y’all are willing to pick either AM or PM and stick with it I think “Noon” and “Midnight” make far more sense.
How do you pronounce “0000 hours”? “Zero-hundred hours”? Or just “Zero Hours”? I think I’d use “Zero-Thousand Hours” since zero and thousand are two of the coolest number-words of all, I think.
Why 10 AM, 11 AM, 12PM ??? it dosn’t make sence to me. It should be 10 AM, 11 AM, 12 AM. Or so I think.
Spelling and grammer subject to change wihout notice.
What would be the correct am/pm for 11:59:59.9999999999… 
(Linking two dope-pain questions into one)
I’d say AM. It’s PM when it rolls over to 12:00:00.
I was never confused by “12pm” or “12am”, but I am sometimes unclear what is meant when someone says “next Tuesday” or “this Saturday”. Obviously, if today is Friday and the speaker says, “this Saturday”, they’re obviously referring to tomorrow. But what if it’s Tuesday? If they say “next Saturday”, do they mean four days from now, or eleven days from now? Because if they meant the Saturday approaching at the end of the current work week, maybe they should have said “this” Saturday.
Have I confused everyone enough?
>Just because a lot of people do something doesn’t make it correct.
Well, if the thing you’re discussing is a convention, it does, doesn’t it? At least if they are in the clear majority?
>http://www.boulder.nist.gov/timefre...tm#Anchor-57026
NIST has perhaps a better claim than anybody else in the world to be authoritative about time. Whether you call it “noon” or anything else, it’s NIST that ultimately decides when it happens!
>The convention is inconsistent, as Polycarp noted, but we still have a convention…
Actually, doesn’t that mean we have two conventions?
“midnight”
“Bedtime”
Yeah, but then you would 12:00 AM followed by 12:01 PM, which seems less consistent than 12:00 PM followed by 12:01 PM.
I don’t know. 12 PM as noon seems absolutely logical to me (even though it is obviously technically incorrect.) I’ve never heard 12 AM being referred to as noon although, as Polycarp has stated, it does appear to happen.
Um, no we couldn’t. 12:01, one minute past noon, has to be “pm” - and the sensible decision was made to match the hour’s designation with that of the rest of the hour.
Typically zero hundred hours. An alternative possiblity is “zero hours, zero minutes”.