Time Zones

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Time Zones

• CGC1D

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The International Date Line

• The International Date Line is a line of
  longitude which follows the 180 degree line and
  passes through the Pacific Ocean.
• It does not completely follow 180 degrees, as it
  zig zags around land masses in the Pacific.
• The purpose of the IDL is to complete the 24 hour
  per day cycle and provide the start of a new day.
• If you cross the IDL traveling eastward you loose
  a day. If you cross the IDL traveling westward,
  you add a day.

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The International Date Line
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Time Zones

• Because the earth rotates continuously, there are
  parts of the earth that are facing the sun, and
  others that are without sun light.
• This rotation is completed within 24 hours and
  completes a cycle per each day.
• Therefore, time is different in different parts
  of the world. This is dependant on the amount of
  sunlight being received.

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Time Zones

• For example, at 12 noon the sun should be
  directly above your location. With the earth
  rotating, only parts of the world will have the
  sun directly above and therefore, receiving noon
  sunlight.

At 12 Noon, the sun would be directly above this
house
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Calculating Time Zone Difference

• Since the earth rotates around its axis once
  every 24 hours, there are 24 time zones with 1
  hour difference between each time zone.
• Since the earth rotates 360 degrees in 24 hours,
  the earth completes a rotation of 15 degrees per
  hour
• (360 /24) 15
• Therefore, each time zone is 15 degrees

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Time Zones
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Calculating Time Zone Difference

• To calculate time difference between two
  locations complete the following
• Steps
• Find the number of degrees difference between the
  two locations.
• Take the number of degrees difference and divide
  by 15. This will find the number of hours
  difference between the two locations.
• Add the number of hours difference if going east.
  OR Subtract the number of hours difference if
  going west.

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Calculating Time Zones

• Example One
• John live in Greenwich, England (0 degrees
  longitude). He plans to make some long distance
  call to relatives in the following cities. What
  time will it be at the following locations when
  it is 1200pm in Greenwich?
• Thunder Bay, Ontario (90 Degrees West)
• Kamloops, British Columbia (120 Degrees West)
• Baghdad, Iraq (45 Degrees East)
• Hong Kong, China (120 Degrees East)

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Time Zones
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Canadas Time Zones

• Canada has six Time Zones. They are
• Newfoundland Time Zone
• Atlantic Time Zone
• Eastern Time Zone
• Central Time Zone
• Mountain Time Zone
• Pacific Time Zone