In a 24-hour day, a.m. and p.m. refer to the two 12-hour periods of the day. A.m. refers to the period between 12:00 in the morning and 11:59 in the late morning, whereas p.m. refers to the period between 12:00 midday and 11:59 in the late evening.Continue Reading
The abbreviation a.m. is derived from the Latin phrase ante meridiem, which translates to "before midday." The abbreviation p.m., also derived from Latin, stands for post meridiem, which translates to "after midday."
The time designations a.m. and p.m. are used when referring to 12-hour clocks. The 24-hour clock, which is used in the military, eliminates a.m. and p.m., instead using the numbers 0000 through 2400 to refer to hours and minutes, with the first two numbers representing hours and the last two numbers representing minutes.
The terms coordinate with the rising, setting and midday position of the sun. Before precise timekeeping came into use, people could tell the time of day based on the sun's position. For example, when the sun crosses the meridian in a specific geographic location, it is noon, otherwise known as midday, signifying the end of the a.m. period and the beginning of the p.m. period. People residing in the same time zone experience noon at the same time, but as they move through time zones, the time differs in one-hour increments.Learn more about Hours, Minutes, & Seconds
To read a military clock, use the 24-hour time system to indicate the hour of the day. The seconds and minutes indicated by the clock are the same as that in a clock following the 12-hour time system.Full Answer >
To convert military time to the standard 12-hour clock, subtract 12 hours from any time shown in double digits. Using this system, 13:00 is 1 p.m. and 23:00 is 11 p.m. for times between 1 and 11:59, the number stays the same and it is in the am; for those between 12 and 12:59, the number stays the same and it is in the pm. Midnight on the 24-hour system is considered to be 00:00.Full Answer >
In the United States the action of "springing forward" occurs on the second Sunday in March. This day begins daylight saving time in most areas of the United States, when clocks are moved forward 1 hour.Full Answer >
To convert standard time to military time, add 12 hours to times after 12 p.m. and remove the punctuation. Military time runs on a 24-hour system without punctuation, while standard time uses a 12-hour system and a colon to separate hours and minutes.Full Answer >