Lesson 4 Time Zones

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Grade 9 Applied Geography - Unit 1
Time Zones
The Earth rotates 15O every hour. The world is divided into 24 15O slices. Within each time zone, all of the people
set their clocks the same way, and each zone is one hour different from the next.
In Canada, there are six time zones: Newfoundland, Atlantic, Eastern, Central, Mountain and Pacific. When it is
12:30 p.m. in Newfoundland, it is
 noon in the Atlantic time zone
 11 a.m. in the Eastern time zone
 10 a.m. in the Central time zone
 9 a.m. in the Mountain time zone
 8 a.m. in the Pacific time zone.
Note: Saskatchewan uses Mountain Standard in the summer and Central Standard in the winter.
All time zones are measured from a starting point centered at England's Greenwich Observatory. This point is
known as the Greenwich Meridian or the Prime Meridian. Time at the Greenwich Meridian is known as
Greenwich Mean Time (GMT) or Universal Time. Kingston is in the Eastern Time Zone in Canada, and it is
designated as GMT minus five hours. When it is noon in the Eastern Time Zone, it is 5 p.m. at the Greenwich
Observatory.
The International Date Line (IDL) is located on the opposite side of the planet from the Greenwich Observatory.
Time Zones - Overview
Canadian Sir Sandford Fleming invented time zones in 1884 to address concerns about intercontinental railway
transportation.
Theory behind Time Zones
 Since the earth rotates around its axis once every 24 hours, there are 24 time zones around the earth, with 1-hour
difference between them. Since the earth rotates through 360 degrees in 24 hours, it rotates through 15 degrees
of longitude in 1 hour (360° / 24 = 15°). Thus, each time zone is 15 degrees wide. Every place within a time
zone has the same time, referred to as its standard time.
 The Prime Meridian is the centre of a time zone that extends 7.5 degrees on either side. Time in this zone is
called universal time (UT) Standard times in other zones are compared to UT. Every 15 degrees is the centre of
a time zone. The earth rotates from west to east. Time zones east of the Prime Meridian have local times that
are ahead of UT. Time zones west of the Prime Meridian have local times that are behind UT.
 Time zone shapes have been modified worldwide. China has one standard time for the whole country despite
the fact that it covers more than 60° of longitude. Canada has six standard time zones, although the boundaries
do not follow the meridians of longitude.
 Some places are located where time zones meet. St. John's, Newfoundland, at 52.5 oW, is located between the
third and fourth time zones west of the prime meridian. Its time is 3.5 hours behind UT.
International Date Line
When sailors first sailed around the world, they returned home either a day ahead or a day behind those people who
stayed. To correct this situation, the International Date Line was established. It runs between the North and South
Pole, and generally follows the 180O line of longitude through the Pacific Ocean. It zigzags to avoid dividing land
masses or island groups belonging to the same country. If you cross the date line moving westward, you add a day.
If you cross the date line moving eastward, you lose a day. The time does not change unless the date line
corresponds to a time zone boundary.
Daylight-Saving Time
Many parts of the world change their time according to the season. During the summer, daylight-saving time is used
to extend daylight hours into the evening when most people are awake. That is, the sun would set at 9 p.m. instead
of 8 p.m., thereby cutting down on energy use since lights don't have to be turned on until later in the day. In Canada
and the United States, daylight-saving time begins on the first Sunday in April and ends on the last Sunday in
October. Other countries use different dates.
Longitude and Time
Early sailors determined their latitude by the angle of the sun above the horizon or by the position of the North Star
(Polaris), but they had no practical way to find their longitude. In theory, longitude could be calculated if sailors
knew their local time and the time in Greenwich. However, the pendulum clocks that were in use at the time did not
work on a ship being tossed about by waves. In 1791, Englishman John Harrison developed the marine chronometer
- spring-loaded clock that could keep time on a moving ship. Longitude was calculated in the following manner:
 Exact local time: 7:00 am
 Greenwich time: 12:00 noon
 Since local time was five hours behind Greenwich, the location was west of the prime meridian.
 5 hours = 75 degrees (5 x 15o)
 Current longitude: 75o W of the prime meridian. Possible locations: Ottawa, Canada; Philadelphia. U.S.A.
Time Zones of Canada – Unique Zones
Newfoundland
Many people wonder why the Province of Newfoundland has a time zone that varies by the half hour rather than the
standard one hour. While the system of Standard Time employs 24 meridians, and each are theoretically the centre
of 24 Standard Time zones, some adjustments have been made to the time zones for the convenience of inhabitants
that lie within the zones. Newfoundland, but not Labrador, lies squarely in the eastern half of its time zone, exactly
three and a half hours from Greenwich. In 1963, the Newfoundland government attempted to bring the province into
conformity with the other Atlantic provinces but withdrew in the face of stiff public opposition.
Nunavut
Normally, Nunavut would have three time zones, but in 2000, it opted to go with one zone: Central Time. To
complicate matters, Nunavut did not use Daylight Savings Time. Thus, Nunavut is Central Time during the summer
and Eastern Time in the winter. In the continuing saga of time in Nunavut, two communities -- Kugluktuk and
Cambridge Bay – adopted Daylight Savings Time and change their clocks in the spring and the fall. In 2001,
Nunavut reverted to three time zones to standardize its time with other parts of Canada.
Other Facts
 Canada uses six primary time zones. From east to west, they are Newfoundland Time Zone, Atlantic Time
Zone, Eastern Time, Central Time Zone, Mountain Time Zone, and the Pacific Time Zone.
 Daylight Saving Time begins at 2:00 a.m. local time on the first Sunday in April. On the last Sunday in
October area on Daylight Saving Time fall back to Standard Time at 2:00 a.m. The names in each time
zone change along with Daylight Saving Time. Eastern Standard Time (EST) becomes Eastern Daylight
Time (EDT), and so forth. Some areas of Canada not using Daylight Saving Time include Fort St. John,
Charlie Lake, Taylor and Dawson Creek in British Columbia, Creston in the East Kootenays, and most of
Saskatchewan (except Denare Beach and Creighton).
1.
Eight Time Zone Facts
The earth rotates about once every 24 hours. There are 24 hours in a day.
2.
The circumference of the Earth is 360°.
3.
Most time zones have a one hour time difference. The exception is Newfoundland Standard Time.
4.
Canada has six time zones: Newfoundland, Atlantic, Eastern, Central, Mountain and Pacific. When it is
12:30 p.m. in Newfoundland, it is
 noon in the Atlantic time zone
 11 a.m. in the Eastern time zone
 10 a.m. in the Central time zone
 9 a.m. in the Mountain time zone
 8 a.m. in the Pacific time zone.
Note: Saskatchewan uses Mountain Standard in the summer and Central Standard in the winter.
5.
Time zones have approximately 15° of longitude from east to west.
6.
The world has 24 time zones (15° x 24 hours = 360°).
7.
Standard times start at 0° longitude running through Greenwich, England. This is called the Greenwich
Meridian or the Prime Meridian.
8.
Standard time was developed by Canadian Sir Sandford Fleming.
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