Time Zones CGC1D. The International Date Line The International Date Line is a line of longitude which follows the 180 degree line and passes through.

Time ZonesTime Zones

CGC1DCGC1D

The International Date LineThe International Date Line The International Date Line is a line The International Date Line is a line of longitude which follows the 180 of longitude which follows the 180 degree line and passes through the degree line and passes through the Pacific Ocean.Pacific Ocean.

It does not completely follow 180 It does not completely follow 180 degrees, as it zig zags around land degrees, as it zig zags around land masses in the Pacific.masses in the Pacific.

The purpose of the IDL is to complete The purpose of the IDL is to complete the 24 hour per day cycle and provide the 24 hour per day cycle and provide the start of a new day.the start of a new day.

If you cross the IDL traveling eastward If you cross the IDL traveling eastward you loose a day. If you cross the IDL you loose a day. If you cross the IDL traveling westward, you add a day.traveling westward, you add a day.

The International Date LineThe International Date Line

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Time ZonesTime Zones

Because the earth rotates Because the earth rotates continuously, there are parts of the continuously, there are parts of the earth that are facing the sun, and earth that are facing the sun, and others that are without sun light.others that are without sun light.

This rotation is completed within 24 This rotation is completed within 24 hours and completes a cycle per each hours and completes a cycle per each day.day.

Therefore, time is different in Therefore, time is different in different parts of the world. This is different parts of the world. This is dependant on the amount of sunlight dependant on the amount of sunlight being received.being received.

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

At 12 Noon, the sun would be directly above this house

Calculating Time Zone DifferenceCalculating Time Zone Difference

Since the earth rotates around its Since the earth rotates around its axis once every 24 hours, there are axis once every 24 hours, there are 24 time zones with 1 hour difference 24 time zones with 1 hour difference between each time zone.between each time zone.

Since the earth rotates 360 degrees Since the earth rotates 360 degrees in 24 hours, the earth completes a in 24 hours, the earth completes a rotation of 15 degrees per hour rotation of 15 degrees per hour

(360 /24)= 15(360 /24)= 15 Therefore, each time zone is 15 Therefore, each time zone is 15 degreesdegrees

Time ZonesTime Zones

Calculating Time Zone DifferenceCalculating Time Zone Difference

To calculate time difference between To calculate time difference between two locations complete the two locations complete the following:following:

Steps:Steps:1.1. Find the number of degrees difference Find the number of degrees difference

between the two locations.between the two locations.2.2. Take the number of degrees difference Take the number of degrees difference

and divide by 15. This will find the and divide by 15. This will find the number of hours difference between the number of hours difference between the two locations.two locations.

3.3. Add the number of hours difference if Add the number of hours difference if going east. going east. OROR Subtract the number of Subtract the number of hours difference if going west.hours difference if going west.

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Calculating Time ZonesCalculating Time Zones

Example One:Example One:• John live in Greenwich, England (0 John live in Greenwich, England (0 degrees longitude). He plans to degrees longitude). He plans to make some long distance call to make some long distance call to relatives in the following cities. relatives in the following cities. What time will it be at the What time will it be at the following locations when it is following locations when it is 12:00pm in Greenwich?12:00pm in Greenwich?

Thunder Bay, Ontario (90 Degrees West)Thunder Bay, Ontario (90 Degrees West) Kamloops, British Columbia (120 Kamloops, British Columbia (120 Degrees West)Degrees West)

Baghdad, Iraq (45 Degrees East)Baghdad, Iraq (45 Degrees East) Hong Kong, China (120 Degrees East)Hong Kong, China (120 Degrees East)

Time ZonesTime Zones

Canada’s Time ZonesCanada’s Time Zones

Canada has six Canada has six Time Zones. Time Zones. They are:They are:• Newfoundland Time Newfoundland Time ZoneZone

• Atlantic Time Atlantic Time ZoneZone

• Eastern Time ZoneEastern Time Zone• Central Time ZoneCentral Time Zone• Mountain Time Mountain Time ZoneZone

• Pacific Time ZonePacific Time Zone