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01������������������������������������������������,The Time

发布日期:2022-01-18 17:41:35 作者: 点击:
Time - AM/PM vs 24 Hour Clock

Normally time is shown as Hours:Minutes

There are 24 Hours in a Day and 60 Minutes in each Hour.

Example: 10:25 means 10 Hours and 25 Minutes

Showing the Time

There are two main ways to show the time: "24 Hour Clock" or "AM/PM":

24 Hour Clock: the time is shown as how many hours and minutes since midnight.AM/PM (or "12 Hour Clock"): the day is split into:the 12 Hours running from Midnight to Noon (the AM hours), andtheother 12 Hours running from Noon to Midnight (the PM hours).

Like this (try the slider):

measure/images/time-am-pm.js

day am pm

AM PM Ante Meridiem*Latin for "before midday" Post Meridiem*Latin for "after midday"Midnight to NoonNoon to Midnight24 Hour:00:00 to 11:5924 Hour:12:00 to 23:59

*Is that spelled "Meridiem" or "Meridian"? See here.

Converting AM/PM to 24 Hour Clock

Add 12 to any hour after Noon (and subtract 12 for the first hour of the day):

For the first hour of the day (12 Midnight to 12:59 AM), subtract 12 Hours

Examples: 12 Midnight = 00:00, 12:35 AM = 00:35

From 1:00 AM to 12:59 PM, no change

Examples: 11:20 AM = 11:20, 12:30 PM = 12:30

From 1:00 PM to 11:59 PM, add 12 Hours

Examples: 4:45 PM = 16:45, 11:50 PM = 23:50Converting 24 Hour Clock to AM/PM

For the first hour of the day (00:00 to 00:59), add 12 Hours, make it "AM"

Examples: 00:10 = 12:10 AM, 00:40 = 12:40 AM

From 01:00 to 11:59, just make it "AM"

Examples: 01:15 = 1:15 AM, 11:25 = 11:25 AM

From 12:00 to 12:59, just make it "PM"

Examples: 12:10 = 12:10 PM, 12:55 = 12:55 PM

From 13:00 to 23:59, subtract 12 Hours, make it "PM"

Examples: 14:55 = 2:55 PM, 23:30 = 11:30 PM

 

Comparison Chart

Here is a side-by-side comparison of the 24 Hour Clock and AM/PM:

Example: on the hourExample: 10 minutes past24 Hour Clock AM / PM24 Hour Clock AM / PM     00:0012 Midnight00:1012:10 AM01:001:00 AM 01:101:10 AM02:002:00 AM 02:102:10 AM03:003:00 AM 03:103:10 AM04:004:00 AM 04:104:10 AM05:005:00 AM 05:105:10 AM06:006:00 AM 06:106:10 AM07:007:00 AM 07:107:10 AM08:008:00 AM 08:108:10 AM09:009:00 AM 09:109:10 AM10:0010:00 AM 10:1010:10 AM11:0011:00 AM 11:1011:10 AM12:0012 Noon 12:1012:10 PM13:001:00 PM 13:101:10 PM14:002:00 PM 14:102:10 PM15:003:00 PM 15:103:10 PM16:004:00 PM 16:104:10 PM17:005:00 PM 17:105:10 PM18:006:00 PM 18:106:10 PM19:007:00 PM 19:107:10 PM20:008:00 PM 20:108:10 PM21:009:00 PM 21:109:10 PM22:0010:00 PM 22:1010:10 PM23:0011:00 PM 23:1011:10 PM Midnight and Noon

"12 AM" and "12 PM" can cause confusion, so we prefer "12 Midnight" and "12Noon".

What Day is Midnight?

Midnight has another problem: there is nothing to tell us "is this the beginning or ending of the day".

holiday

Imagine yourfriends say they areleaving for holiday at "midnight" on 12th March, what day should you arrive to say goodbye?

Do you get there on the 11th(assuming they leave at the very start of the 12th), or the 12th (assuming they leave at the end of the 12th)?

It is better to use:

11:59 PM or 12:01 AM, or23:59 or 00:01 (24-Hour Clock)

which the railroads, airlines and military actually do.

So, when you see something like "offer ends midnight October 15th" tell them to use one minute before or after so there is no confusion!

 

Footnote on"Meridiem" vs "Meridian"

Should "AM"be "ante meridiem"or "ante meridian" (likewise for PM)?

The official (according to an American,Australian and Britishdictionary),and most common, spelling for AM is"ante meridiem" which is a Latin phrase. I recommend that spelling!

But people sometimes use the phrase "ante meridian" (a "meridian"in this case refers to an imaginary line in the sky when the sun is at its highest point).

 

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