The 24 Hour Clock

The day is divided into 24 hours, 12 in the morning and 12 in the afternoon. Hence when we say "eight o'clock" we could be talking about either eight in the morning or eight in the evening. Normally the meaning is obvious from the context, if there's likely to be any uncertainty then we suffix the time with "am" or "pm".

That's fine for normal usage, however there are some situations where we can't take any risk of confusion. There are also situations such as railway timetables where the am/pm notion would be clumsy. This is where the 24 hour clock comes in.

What is the 24 Hour Clock?

The idea behind the 24 hour clock is simply to give every minute of the day a unique designator. This is done by counting the number of hours and minutes since midnight.

All this really means is adding 12 to all times after noon. Thus eight thirty in the morning remains 8:30 whilst eight thirty in the evening becomes 20:30 (because 8+12=20).

Converting from the 24 hour clock to the 12 hour clock is the reverse: if the hour number is less than twelve, leave things as they are and call it morning. If the hour number is greater than 12 than subtract 12 and call it afternoon.

Military Time

A situation where clear communication is essential is in the military and the 24 hour clock is sometimes called military time. To further avoid misunderstanding the time is usually read out explicitly. Thus 8:30 in the morning - 08:30 - is spoken as "oh-eight-thirty". Eight o'clock in the evening - 20:00 - is spoken as "twenty-hundred". This isn't scientifically accurate but serves the purpose of communication.

Midnight

Midnight sometimes cuases people some confusion. Remember that the 24 hour clock measures time since midnight. Thus one minute before midngight is 23:59, midnight is 00:00 and one minute after midnight is 00:01

Analog Clocks

The traditional analogue clock face shows the numbers 1 through 12. The hour hand makes two complete sweeps in a day. Wouldn't it be more sensible to have a 24 hour face and show the whole day?

Perhaps. However showing twice as many hours means twice as much accuracy in the mechanism, which would no have been easy for early clock and watchmakers.

That said, there have always been people who prefer a 24 hour dial. Today there are a number of 24 hour clocks and watches you can buy and they make an unusual timepiece.

	All About Clocks, Watches and Time
The 24 Hour Clock The day is divided into 24 hours, 12 in the morning and 12 in the afternoon. Hence when we say "eight o'clock" we could be talking about either eight in the morning or eight in the evening. Normally the meaning is obvious from the context, if there's likely to be any uncertainty then we suffix the time with "am" or "pm". That's fine for normal usage, however there are some situations where we can't take any risk of confusion. There are also situations such as railway timetables where the am/pm notion would be clumsy. This is where the 24 hour clock comes in. What is the 24 Hour Clock? The idea behind the 24 hour clock is simply to give every minute of the day a unique designator. This is done by counting the number of hours and minutes since midnight. All this really means is adding 12 to all times after noon. Thus eight thirty in the morning remains 8:30 whilst eight thirty in the evening becomes 20:30 (because 8+12=20). Converting from the 24 hour clock to the 12 hour clock is the reverse: if the hour number is less than twelve, leave things as they are and call it morning. If the hour number is greater than 12 than subtract 12 and call it afternoon. Military Time A situation where clear communication is essential is in the military and the 24 hour clock is sometimes called military time. To further avoid misunderstanding the time is usually read out explicitly. Thus 8:30 in the morning - 08:30 - is spoken as "oh-eight-thirty". Eight o'clock in the evening - 20:00 - is spoken as "twenty-hundred". This isn't scientifically accurate but serves the purpose of communication. Midnight Midnight sometimes cuases people some confusion. Remember that the 24 hour clock measures time since midnight. Thus one minute before midngight is 23:59, midnight is 00:00 and one minute after midnight is 00:01 Analog Clocks The traditional analogue clock face shows the numbers 1 through 12. The hour hand makes two complete sweeps in a day. Wouldn't it be more sensible to have a 24 hour face and show the whole day? Perhaps. However showing twice as many hours means twice as much accuracy in the mechanism, which would no have been easy for early clock and watchmakers. That said, there have always been people who prefer a 24 hour dial. Today there are a number of 24 hour clocks and watches you can buy and they make an unusual timepiece. Clocks-Watches-Time / Time / 24 Hours / 24 Hour Clock / All original material copyright © Trevor Mendham 2005-2008. All trademarks are the property of their respective owners Please read the site terms of use		Clocks Watches Time 60 24 Hours 24 Hour Clock 7 Days Arrow Atomic Bells Biological Calendars Daylight Saving Leap Seconds Planck Quotes Solar Standard Travel Zones Time & Motion More...