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Time Zones. Earth Science Chapter 6. Earth is divided into 24 time zones, each about 15 degrees of longitude wide and exactly one hour different from the zones on either side of it. The United States has 6 time zones:Eastern Standard Time,
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Time Zones Earth Science Chapter 6
Earth is divided into 24 time zones, each about 15 degrees of longitude wide and exactly one hour different from the zones on either side of it. The United States has 6 time zones:Eastern Standard Time, Central Standard Time,Mountain Standard Time, Pacific Standard Time,Alaska Standard Time, Hawaii Standard Time
Calendar dates begin and end at midnight • the International Date Line is located near the 180° meridian
Time Zones North Pole Direction of Rotation
24-hour day means 24 time zones 360° in a circle 360°/24 hours = 15°/ hour Why do we Have time zones?
The “Prime Meridian” (first meridian) Location: Greenwich, England Lines of Longitude O° E/W Longitude 180°
EAST O° E/W Longitude 180°
WEST O° E/W Longitude 180°
8PM 4/20 9PM 4/20 7PM 4/20 6PM 4/20 Notice how the time zone for Greenwich, England starts at 7.5°W and ends at 7.5°E! 0° longitude is in the middle of the time zone! 0° 5PM 4/20 As you travel East, the time becomes LATER by 1 hour for each time zone! Each time zone is 15° wide!
4AM 4/21 6AM 4/20 Note: move across the IDL to the East-you lose a day Move across the IDL to the West-you gain a day Notice how the International Date Line lies within a time zone! 180° longitude is in the middle of the time zone! 5AM 4/21 International Date Line (180°) 5AM 4/20 As you travel East, the time still becomes LATER by 1 hour for each time zone! But, as you cross the I.D.L., there is NO time change, only a date change! (earlier date, when going East!)
165°E As you travel farther East, you reach the Western hemisphere by crossing the I.D.L.! (Time zone A) 4AM 4/21 5AM 4/20 (Time zone B) 180° (I.D.L.) (Time zone B) 5AM 4/21 Crossing the I.D.L. E to W: You go forward one day, while time is unchanged! (Time zone C) 6AM 4/20 165°W
West East A B C D E F G H I (I.D.L) Practice… If the date and time in time zone “C” is 9/12 and 5:00PM, a) What is the date and time in time zone “A”? b) What is the date and time in time zone “E”? c) What is the date and time in zone “G”? d) What is the date and time in zone “H”? e) What is the date and time in time zone “I”? 9/12, 3:00 PM 9/12, 7:00 PM 9/12, 9:00 PM 9/11, 9:00 PM 9/11, 10:00 PM