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What is Zulu time format?

Posted by  Josh  on  July 7, 2019  in   Zulu Time

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You might have noticed a 4-digit number (Zulu Time) with the letters “Z” or “UTC” listed at the bottom or top of satellite images, radar, and maps. The line of letters and numbers is a timestamp. It shows the time the text discussion or the weather map was issued and when its forecast is right. A form of standardized time, known as the Z time is used instead of the local P.M. and A.M. hours.

ZULU TIME | militarytimesclock.com

Zulu time or Z Time?

Zulu Time is a Global Time zone that was created to prevent confusion about time zones and daylight saving time. First, to create time zones, start somewhere. That place, the starting point, is referred to as the ‘Prime Meridian’.

Zulu Time history

Britain was the foremost maritime power of the world during the introduction of the latitude and longitude. The starting point for the zero degrees Longitude was the “prime meridian” that goes through the Royal Greenwich Observatory, England, southeast of central London.

At the era when time zones were first introduced, the “starting point” was and still is at the Royal Greenwich Observatory. Whenever it is noon at the observatory, it is six hours earlier in Chicago, eight hours earlier in Los Angeles, five hours earlier in Washington, and seven hours earlier in Denver.

Washington in 1884

Until the 19th century, every country and city had its own starting point such that when it was 7:15 in one city, it was 7: 30 in another one. With technological advancements that led to the telegraph and railways, there was a need to come up with an International Starting Point.

The starting point was later called the Prime Meridian and it was divided into equal 24 segments around the globe. Therefore, when it is 7:00 in a specific city, it will remain at 7:00 in the other city too, until it gets to the 8:00 Time Zone; there will be no time differences (7:15, 7:20, or &:30) at the cities in between 25 nations met in Washington in 1884 and decided which Prime Meridian would be used on the entire planet.

Britain had the strongest position because most ships were using the Prime Meridian, together with the US railways.

The conference had to discuss an Ending point or an International Date Line where the calendar was to move to the next date. Greenwich, England was the favorite choice because its end would be around Alaska. Currently, the Greenwich Mean Time is called Universal Time Coordinated (UTC) commonly known as Zulu Time.

Why do we use Zulu time?

Z time is utilized in order that all weather measurements taken from different locations and varying time zones around the globe may be made at the same time.

Why is it called Zulu time ?

Civil Aviation and the Navy use the letter Z phonetically to represent ‘Zulu’, the time at the Prime Meridian. The U.S time zones are Hawaii (‘W’, Whiskey), Mountain (‘T’, ‘Tango’), Eastern (‘R’, ‘Romeo’), Alaska (‘V’, ‘Victor’), Central (‘S’, ‘Sierra’) and Pacific (‘U’, ‘Uniform’). The official timekeeper of the United States is the Department of the Navy; the U.S Naval Observatory, Washington, D.C houses the Master Clock facility.

Z Time and Military Time

Slight differences exist between military time and Z time. Most of the time, the two can be easily misunderstood. Z time, also known as GMT time is based in the 24- hour clock.

The military is also based on a 24-hour clock that operates from midnight to midnight. However, for the Z time, its midnight is calculated with reference to the midnight local time at the 0o longitude, the prime meridian that passes through Greenwich, England. As an alternative, the time 0000 will always describe midnight local time regardless of the global location.

Moreover, 00Z will always correspond to midnight only in Greenwich. 00Z can vary from 7 or 8 PM along the east coast or from 2 PM local time in Hawaii in the United States.

The easiest way to calculate Z Time

At times, calculating Z time can be quite the task. Using the following tips will make it easier to calculate manually. A table by the NWS also shows how calculating Z time is easy.

How to convert Local Time to Z Time

How to calculate Zulu time

  • Convert the 12-hour to 24-hour
  • Find your specific time zone “offset”
  • Add your time zone offset to the converted military time. The sum of both is equal to the present Z time

The table below shows the U.S Time zone Offset

Standard Time Daylight Saving Time
Eastern -5 hours -4 hours
Central -6 hours – 5 hours
Mountain -7 hours -6 hours
Pacific -8 hours -7 hours
Alaska -9 hours
Hawaii -10 hours

Converting Z Time to Local Time

  • Deduct the time zone offset amount from the given Z time. That will be the current military time.
  • Convert the 24-hour hour to 12-hour

An important factor to always remember is the 24-hour clock 23:59 is the concluding time before midnight, and 00:00 begins the first hour of a new day.

Comparison between Z Time, UTC and GMT

Frequently, the Z time is quoted alongside Greenwich Mean Time (GMT) and Coordinated Universal Time (UTC). Still, they are not the same.

Zulu time is useful in ship and plane navigation. It is primarily used in military operations and aviation as well. In addition, international shortwave broadcasters in their program schedules and broadcasts use it Zulu time. Utility radio services, the military, Ham radio operators, and shortwave listeners are big users of the time as well.

The United States Military and the Chinese Military among several others have a list of specific names for the time zones across the world. All the names utilize the NATO phonetic alphabet that represents 26 letters of the alphabet; the phonetic alphabet uses easily recognizable words.

The Zulu time zone is among the words. There are also numerous time zones that incorporate the same offset. They are Azores Summer Time (AZOST), Western European Time (WET), Eastern Greenland Summer Time (EGST), Western Sahara Standard Time (WT), and of course the Greenwich Mean Time (GMT).

An email sent from someone in the Zulu Time Zone (Z) will have the time zone indicated as “+0000” at the headers of the mail. But +0000 does not only show Zulu Time Zone since other time zones could have that same effect.

Places where Zulu Time is observed

As mentioned earlier in the article, Zulu Time Zone, denoted by the suffix Z, is also known as UTC+ 0. This time zone is used regularly at sea between the longitudes 7.50 West and 7.50 East. 0800Z is pronounced as “Zero eight hundred Zulu”. Places that experience the same time as Zulu time Zone are:

  • Accra, Ghana
  • Casablanca, Morocco
  • Monrovia, Liberia
  • Reykjavik, Iceland
  • Bissau, Guinea-Bissau
  • Conakry, Guinea
  • Rabat, Morocco
  • Bamako, Mali
  • Yamoussoukro, Ivory Coast
  • Ouagadougou, Burkina Faso
  • Nouakchott, Mauritania
  • Freetown, Sierra Leone
  • Lome, Togo
  • Dakar, Senegal
  • Bamako, Mali
  • Bangui, Gambia
  • Sao Tome, Sao Tome, and Principe

Only 17cities are mentioned but there are others, which observe Zulu Time Zone too.

  • Pacific Standard Time (PST) is 8 hours behind Zulu
  • Eastern Standard Time (EST) is 5 hours behind Zulu
  • Mountain Standard Time (MST) is 7 hours behind Zulu
  • Central Standard Time (CST) is 6 hours behind Zulu