Podcast
Questions and Answers
What was the issue with the old way of defining local time?
What was the issue with the old way of defining local time?
What is the purpose of Coordinated Universal Time (UTC)?
What is the purpose of Coordinated Universal Time (UTC)?
What is the relationship between neighboring time zones?
What is the relationship between neighboring time zones?
What is the significance of the prime meridian?
What is the significance of the prime meridian?
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What is the designation for the time zone at the prime meridian?
What is the designation for the time zone at the prime meridian?
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What is the relationship between time zones east of the UTC zone?
What is the relationship between time zones east of the UTC zone?
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What is the name of the time zone that includes most of western Europe?
What is the name of the time zone that includes most of western Europe?
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Why are time-zone boundaries sometimes modified?
Why are time-zone boundaries sometimes modified?
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What is the angular span of each time zone?
What is the angular span of each time zone?
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How many time zones are there in North America?
How many time zones are there in North America?
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Study Notes
Time Zones
- Each town had its own local time before the 1800s, with noon being when the sun was highest in the sky.
- Railroad companies created standard time zones in the 1800s to enable precise schedules, and it was eventually adopted worldwide.
Calculating Time Zones
- The Earth makes one complete revolution in one day, covering 360° of longitude.
- Each hour of elapsed time spans 15° of longitude, resulting in each time zone spanning approximately 15° of longitude.
- This means neighboring time zones are usually 1 hour different from each other.
Time Zone Characteristics
- All clocks within a time zone are set to the same time.
- Time-zone boundaries are sometimes modified to follow political or geographic boundaries for commercial purposes.
Coordinated Universal Time (UTC)
- UTC is the time zone at the prime meridian, also known as Greenwich Mean Time (GMT) and Zulu time (Z).
- The prime meridian is in the middle of the UTC time zone, spreading 7.5° on each side.
- UTC is the official time used in meteorology for coordinating simultaneous weather observations worldwide.
International Time Zones
- Time zones are designated by letters A-Z, with Z being at Greenwich.
- East of the UTC zone, local time zones (A, B, C, ...) are ahead of Greenwich time, while west of the UTC zone, local time zones (N, O, P, ...) are behind.
- Each zone can have multiple local names, depending on the countries it spans.
Examples of Time Zones
- Most of western Europe is in the Alpha (A) zone, also known as Central Europe Time (CET) or Middle European Time (MET).
- North America has 8 time zones, designated by letters P to W.
International Date Line
- The international date line is near 180° longitude in the middle of the Pacific Ocean.
- When traveling east to west across the date line, you lose a day, while traveling west to east, you gain a day.
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Description
Learn about the history of time zones, how they were established, and their importance in modern communication and transportation.
