zones, each containing 15 degrees of longitude.
The first 15-degree time zone centers on
the Prime Meridian (0 degrees longitude).
Each successive time zone, east and west,
centers on the next 15 degrees of longitude, or 0, 15, 30, 45, 60 and so on.
High noon moves westward as the earth
rotates west to east relative to the sun. As
high noon passes over the central meridian of a time zone, the entire zone (7.5 degrees east and west of the central meridian) experiences noon at the same moment.
Although most of the world adopted standard time zones, some adjustments were
necessary. For example, when a state or
city was divided into two different time
zones, the boundaries between the time
zones were often arbitrarily moved to create one time zone.
The United States, including the western states of Alaska and Hawaii, has six
time zones. From east to west, they are
based on the central meridians of 75, 90,
105, 120, 135 and 150 degrees west longitude. These time zones have geographic
names: Eastern, Central, Rocky Mountain,
Pacific (or West Coast), Alaskan and Hawaiian time zones.
Because the U.S. Eastern Time Zone is
centered on 75 degrees west, or five time
ever, it was not until Magellan’s crew returned from their circumnavigation of the
earth in 1552 that evidence materialized of
an impending problem with recordkeeping. The ships’ logs were one day behind.
This occurred because the ships had sailed
westward around the earth. During the
three-year long voyage and while travelling the same direction that high noon
Neal Lineback
moves, the ships “lost” a day.
The solution to the lost day was solved
and Mandy Lineback Gritzner
by creating the International Date Line,
conveniently located on the 180th meridian
in the middle of the Pacific Ocean. New
dates on the calendar begin at the International Date Line. For example, while it
may be 2:45 p.m. Sunday immediately to
the east of the date line, it will be Monday
Summer vacation often involves travel
at 2:45 p.m. to the west.
across multiple time zones by aircraft or
Scientific evidence shows that crossmotor vehicle. As families cross domesing time zones is stressful to the human
tic and even international time zones, the
body. Airline crewmembers and passentime change can temporarily affect sleep
gers who often cross many time zones can
patterns and moods, even causing irritasuffer problems as serious as short-term
bility, stomach problems and decreased
psychiatric disturbances and disruption of
mental acuity.
menstrual cycles in women according to a
Until 1884, most of the world used its
Reuters article.
own local time. Clocks were set based
Disorientation, fatigue and sleeplesson high noon, the time when the sun apness associated with crossing time zones is
peared highest in the sky each day. As a
called jet lag. The condition is more severe
result, two towns located just a few miles
for older travelers and those crossing more
apart had lothan
three
cal times that
time
zones.
World Time Zones
were a few
Furthermore,
18
14
minutes apart.
the
direc©2010
Local time
tion
of
travel
16
15
19
was adequate
can affect jet
17 19
21
until the raillag—flights to
road and the
the east cause
+0.5
hrs
telegraph
more jet lag
+0.5
hrs
emerged.
than
flights
Printing unto the west in
derstandable
most people.
train
schedW h i l e
ules
based
there is no
+ 0.5
on local time
cure for jet
hrs
at every stop
lag, travelers
Geography in the News 8/6/10 Tory Smith
was
imposcan attempt
sible.
to adjust the
24
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 1
Because
body’s clock
of increasing
by trying to
Sources: GITN #229, “World Time Zones,” November 4, 1992; and http://www.abc.net.au/science/
problems with
stay alert and
news/stories/2007/1887185.htm
local time, an
in the sun
international
during
the
congress was assembled in 1884 to estabday when they arrive at their destination
zones west of the Prime Meridian, the
lish standard world time zones. The world
and waiting until nightfall to sleep. Happy
time in Washington, D.C., is five hours
is divided into 360 degrees of longitude,
traveling!
earlier than the time in London (Green180 degrees west and 180 degrees east of
And that is Geography in the News™. Auwich Time). In other words, if a business
the Prime Meridian, which passes through
gust 6, 2010. #1053.
call must be made from Washington to
Greenwich, England. Longitude lines, or
Co-authors are Neal Lineback, Appalachian
London during working hours, it must be
meridians, are imaginary lines extending
State University Professor Emeritus of
made before noon, or it will not reach Lonfrom pole to pole and measuring distances
Geography, and Geographer Mandy Lineback
don before 5 p.m. there.
east and west. Since each day has 24 hours,
Gritzner. University News Director Jane
The ancient Greek and Roman scholars
the congress divided the earth into 24 time
Nicholson serves as technical editor.
understood earth-sun relationships. How-
Geography
In The
News™
TIMES ZONES
AFFECT SUMMER
TRAVEL
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