Hello! This week on
Ask a Teacher
, we will answer a question from Max in China about the difference between a.m. and p.m.
Question:
This is Max from China. During a listening exam I heard a saying like this, “The incident happened on the 400 block of Rutland Road just after 12:30 PM,” and it was described as midnight. I’m
confused
. I think that 12:30 PM should be at noon during the day, and if I want to say the time of midnight I think AM is correct. Which one is right? Thank you for helping me solve this problem.
Best regards,
Max
Answer:
Dear Max,
Thank you for writing to us.
You are correct! In the United States, we do not use a 24-hour clock in day-to-day speech. But some special fields that demand very clear communication use a 24-hour clock. So, you might hear a person describe such time as “military time.” A 24-hour clock is more commonly used internationally than it is in America.
We use a 12-hour clock and
abbreviations
from Latin to tell time, a.m. (
ante meridiem
, meaning before midday) and p.m. (
post meridiem
, meaning after midday).
Our morning clock starts at 12:00 a.m. That is 0:00 (zero hundred hours), or midnight, internationally.
Morning, or a.m. hours, go until 12:00 p.m., which would also be 12:00 on an international, 24-hour clock.
But most of the time, we do not show a difference between the two forms of timekeeping in everyday speech. For example, we know that, if a friend wants to meet at 2:00 local time, hopefully they do not want to meet at 2:00 in the morning.
Let us look at a few examples to compare times.
My supervisor planned the meeting for 3 p.m.
This means that the meeting will take place at 3:00 in the afternoon.
That new superhero movie is so long; it lasted until 1 a.m.
