Geography 140
Introduction to Physical Geography
Lecture: Geographic Grid and Time
Time Zones, Daylight Saving Time, and the Date
V. In discussing the geographic grid, we saw that longitude and time are
closely related: Determining longitude is basically a matter of
converting the difference in time between two places into a difference in
longitude. In this lecture, I'll go over a few plot complications on
this basic theme.
A. Standard time (time zones)
1. Your watch is not keeping correct sun time. That is, it does not
show 12:00 when the sun is due south of us at its highest point of
the day. There are two sources for this discrepancy:
a. Remember that bit about sun slow and sun fast time in the third
lecture about revolution at various points in the year? The sun
will hit the highest spot in the sky somewhat sooner than "noon"
on your clock from the July aphelion until the January
perihelion, and it will arrive somewhat later than "noon" on
your clock from the January perihelion until the July aphelion.
This discrepancy has to do with the equation of time related to
our planet's elliptical orbit.
b. The other BIG reason is your watch keeps local ZONE time, not
local sun time, and the next section of this lecture will deal
with zone time, aka standard time.
2. Standard time is fairly new.
a. It used to be that we all independently set our watches to fit
the local sun time at our exact location. Very commonly, a
local church tolled the hours based on a sundial's readings, and
everyone either reckoned time by the tolling or set their clocks
or watches when the bells tolled.
b. This worked just fine, since very few people travelled around
much. If you moved around, even as little as 150 km, your watch
would be out of synch with the local sun time, and you'd be
constantly having to adjust your watch (or missing the
appointments you'd travelled to have!).
c. It became an issue when railroad construction began to open up
travel opportunities and needs in the nineteenth century. For
most people, this discrepancy between your watch and the local
sun time was a minor inconvenience, but for the railroads it was
a very serious problem, indeed. As train traffic increased, it
became difficult to coördinate the locations of trains and
the times they were to be on particular stretches of track. It
wouldn't do to have two trains, each assiduously trying to keep
its own local time accurately, arrive at the same siding on the
same time! So the railroads developed zone time.
d. One Dr. William Hyde Wollaston (1766-1828) in England came up
with the idea, and it was touted by Abraham Follett Osler (1808-
1903). A British railroad, the Great Western Railroad, adopted
London standard time for the first time in November 1840.
e. The US and Canadian railroads quickly got with the program, too,
the more so, since these two huge countries span a lot of
longitude. They coördinated themselves and went on
standard time on 18 November 1883.
f. Not everyone thought this was the bee's knees, though. A lot of
people thought it violated religious precepts, tinkering with
God's good time, and there was an amusing episode when the City
Council of Detroit decreed that the city would go on standard
time in 1900, and only half the city complied. You can imagine
the chaos. They didn't iron out the mess until 1905, when they
finally got everyone onto Central Standard Time! In 1918,
Congress belatedly got onto the bandwagon and decreed that the
United States would officially adopt Standard Time.
3. The idea behind standard time is that everyone in a standard time
zone agrees to keep the WRONG time but the SAME time for safety and
convenience.
4. Nowadays, the entire world is, theoretically, divided into 24 time
zones, each one roughly 15° (or one hour) wide. Within them,
the time is based on the correct mean sun time of a central
meridian. The central meridians are those the longitudes of which
can be evenly divided by 15°: 0, 15, 30, 45, 60, 75, 90, 105,
120, 135, 150, 165, and 180 degrees of longitude, east or west.
5. In the contiguous 48 United States, we have four such zones, with
an additional three zones for the two states and a commonwealth
outside the contiguous 48, each with a descriptive name:
a. Pacific Standard Time Zone, in which everyone keeps the time
prevailing at 120°W, so we all pretend to live in Fresno!
We in Long Beach are located at 118°W, so we're 2° from
our central meridian, meaning that our clocks run about 8
minutes slower than our mean sun time. Our zone time is 8 hours
earlier than Greenwich Mean Time, that is, it's -8 hours,
Universal Time.
b. Mountain Standard Time Zone is centered on long. 105°W., or
-7 hours UT.
c. Central Standard Time Zone is centered (sorry) on long.
90°W, or -6 hours UT.
d. Eastern Standard Time Zone is centered on long. 75°W., or -5
hours UT.
e. Most of Alaska keeps Alaskan Standard Time, centered on long.
135°W (-9 hours UT), Hawai'i keeps Hawai'i-Aleutian Standard
Time, centered at 150°W (-10 hours UT), and Puerto Rico is
in the Atlantic Standard Time Zone, centered on long. 60°W
(-4 hours UT).
7. Globally, no-one else gives a hoot about the cutesy names we've
given our zones, just like we don't much care what the folks in,
say, Estonia call theirs (Eastern European Standard Time Zone, in
case you're curious, though I have no idea what that sounds like in
Estonian!). So, internationally, there is a system of letters
assigned to the various zones: Unfortunately, it doesn't follow a
coherent system.
a. Greenwich is Z, for 0 UT (sometimes called Zulu Time, though the
old Zulu Empire is today 2 hours later than Greenwich).
b. All zones east of there up until the International Date Line
(180°) are named "A" (+1 hour UT), "B" (+2 hours UT,
including the Zulu Empire in today's South Africa), "C" (+3
hours UT), ... to "M" for most of the western half of the zone
straddling the IDL.
c. All zones west of the Greenwich zone are lettered, still in
ascending order, from "N" (-1 hours UT), "O" (-2 hours UT), "P"
(-3 hours UT), ... to "X" for most of the eastern half of the
zone stradding the IDL.
8. So that means that our International Zones are:
a. Atlantic Standard Time = "Q"
b. Eastern Standard Time = "R"
c. Central Standard Time = "S"
d. Mountain Standard Time = "T"
e. Pacific Standard Time = "U"
f. Alaska Standard Time = "V"
g. Hawai'i-Aleutian Standard Time = "W"
9. And, just to be difficult, not all countries play by the
15°/one hour rule:
a. A few are centered on intermediate central meridians, so that
they're offset by half an hour, instead of a full hour (e.g,
Iran, which is +3:30 UT; Newfoundland, the easternmost of
Canada's provinces, is -3:30 UT; and India, at +5:50 UT).
b. A few very sparsely populated places don't participate in it at
all, the Empty Quarter in Saudia Arabia, for example.
10. And yet another plot complication: The boundaries of these zones
do not fall exactly on the theoretical boundary meridians (which
are supposed to be halfway between each pair of central meridians).
You can see the mayhem on the international level here:
The boundaries follow meridians over the oceans and then zig and
zag all over on land. This happens for a couple of reasons:
a. Most smaller countries and states find it administratively
convenient to have their entire jurisdiction in one time zone:
i. The boundary between international zones P and Q runs up
the Andes, along the boundary between Chile and Argentina
in southernmost South America (interestingly, the
Falklands/Malvinas island group to the southeast of
Argentina, is in the Q zone -- Britain and Argentina both
claim them, but the British hold them, and their use of the
Q zone seems to underscore their claim to them).
ii. Allllllllllllll of the People's Republic of China is in the
H zone, the boundaries to which then flow along much of the
PRC's borders.
iii. The boundary between U and T runs right up the border
between Nevada and Utah and, farther north, between the
Canadian provinces of British Columbia and Alberta.
b. Even this will be adjusted further if there is a compelling
economic argument for including smaller areas in a time zone
different than the country, state, or province it's in. We see
lots of examples at the scale of the American
contiguous 48 states (be patient -- this is a large graphic
file, and it takes a while to download):
i. Take a look at the Pacific Northwest: The boundary between
Pacific (U) and Mountain (T) standard time zones zigs
around some counties in eastern Oregon and northern Idaho.
ii. You see lots of this in the Great Plains states: western
Kansas, Nebraska, South Dakota, and North Dakota.
iii. Allllll of the great state of Texas is in Central Standard
Time (S), ..... except the westernmost county in which El
Paso is located. El Paso is the Bright Lights of the Big
City for a lot of people living just over the western state
border in New Mexico, who would find commuting daily
between time zones would be a serious pain.
iv. Another example of a zig and zag around a commuting field
is found up around Chicago, which is in the state of
Illinois on the southwest end of Lake Michigan: A lot of
Chicago Loop commuters live in the northwest corner of
Indiana, and a bunch of people living in South Chicago
commute to Gary, Indiana. Notice how the border bends
around the northwesternmost counties of Indiana.
11. Standard Time is wonderful: It promotes safety and convenience by
getting everyone in a region to agree to keep the wrong time but
the same time. It does create some problems, though. The big one
is that we are confronted with sudden one hour time changes as we
leave one time zone for the next, and there we sit, wondering what
to do with the *&@$%?! watches and dashboard clocks. Here's the
secret (and a way around the confusing nature of the English
language, which misleads us here).
a. As you go from east to west (e.g., driving from Boston to San
Francisco), you RELIVE an hour each time you cross a time zone
boundary (yeah, like that exciting stretch on I-80 heading out
of North Platte, Nebraska). So, what do you do with your clock
if you get to relive an hour? You set it BACK an hour.
b. As you go from west to east (e.g., from Los Angeles to Atlanta),
you SKIP an hour each time you cross a time zone boundary (gosh,
wouldn't it be awfully nice to skip that lonesome stretch
through the Llano Estacado on US 70 from Roswell, NM through
Clovis, NM, to Lubbock, TX?). Since you skip an hour, what will
you be doing with the dashboard clock (after getting out your
car owner's manual <G>)? To skip an hour, you'd set the
clock FORWARD an hour.
c. Notice I haven't used the words, "gain" and "lose" an hour?
That's because English is sometimes distressingly ambiguous. To
"gain" an hour means to relive an hour and set the clock back,
but most of us hear the word "gain" as a mathematical direction
and add an hour (as in from 10 am to 11 am), right? To "lose"
an hour, means to skip it, but we often think "lose? okay,
subtract an hour, from 10 am to 9 am). It is, therefore, NOT a
good idea to use the expressions, "gain" and "lose" an hour.
Instead, think, "I relive an hour as I cross a time zone
boundary going west, and I skip an hour there if I'm going
east." Thinking of it this way will keep you in an unconfused
state. I hope.
d. With respect to telephone calls, plane flights, and such, places
EAST OF you are LATER than you, and places WEST OF you are
EARLIER than you, one hour for every time zone boundary in
between you. Alternatively, if YOU are east of someplace, YOU
are later than that place, and, if YOU are west of someplace,
YOU are earlier than that place.
i. For example, we are west of Greenwich (our nearest central
meridian is 120°W, or -120°, so we are earlier than
Greenwich. If it's 11 pm there, it's 3 pm here.
ii. New York is east of us, in Eastern Standard Time. That
means that there are three time zone boundaries between us,
which means that NYC is 3 hours later than we are: If it's
11 am here at the Beach, it's 2 pm there.
iii. If you want to call your Aunt Bertha in Chicago (two time
zones east of us), and you know the dear soul retires each
night at 9 pm, you'd better make sure to call her before
what time our time? 9 - 2 = 7 pm here.
iv. Let's say you fly from Boston to Los Angeles. You're on
the red-eye economy flight leaving Logan at 10 pm. The
flight normally takes six hours in this direction (it's
usually about five going from here to there, due to the Jet
Stream, but that's another lecture). Sooooo, when should
your DEAR friends be awaiting your arrival at LA-X? The
plane leaves Boston at 10 pm EST. There are three time
zone boundaries to cross (EST-CST; CST-MST; MST-PST), so
there are three hours of time difference between L.A. and
Boston. L.A. is west of Boston, so that means L.A. is
three hours EARLIER. Soooo, the plane leaves Boston at 7
pm, Los Angeles time. Add 6 hours of flying time to 7 pm
(7+6=13, oops, that's an hour past midnight). So, the plane
arrives at 1 am -- you'd better have VERY dear friends, if
you pull this on them).
B. Daylight Saving Time is another geographic grid and time topic.
1. Daylight Savings was first instituted in the US towards the end of
World War I, for seven months in 1918 and 1919. The idea was to
save fuel for the war effort by getting people to go to bed
earlier, so they'd shut off the darn lights already. By getting
them out of bed earlier in the mornings in the summer, too, you'd
get them to utilize the earlier daybreak in summer, which would
also help shave the electricity bills. Now, even paroxysms of
patriotism are not likely to motivate most folks into hitting the
hay any sooner (maybe our Inner Child is rebelling against our
Inner Parents who are ordering us to go to bed and stay there?).
So, the government decided to trick 'em into it. That's what
Daylights Savings is all about: snookering us into bed sooner than
we'd like to go. The idea was that we would feel better about
going to bed at 10 pm if we could call it 11 pm. This was one
unpopular law and Americans rose up and forced Congress to abolish
it in 1919, over President Wilson's veto.
2. Then, World War II hit. The United States went back on Daylight
Saving Time, again to conserve fuel for the war effort. It stayed
on year-long Daylight Savings for a few years this time, from 2
February 1942 through 30 September 1945. People got used to it (or
resigned to it), and it lingered after the War.
3. From 1945 to 1966, though, the Federal government didn't mandate
it, so states and counties and even cities were free to choose DST
or not. Well, states' rights and all, the result was a crazy quilt
of areas observing DST and not, of areas implementing it at one
time of the year and others choosing a different date. It was
getting kind of nutty. It was more than just kooky, however, for
certain economic interests: broadcasters and bus and train and
plane lines. All this local color was creating ticked-off
customers and general confusion. One memorable example was that,
on one dinky little stretch of Route 2, just 35 miles worth,
between Moundsville, WV, and Steubenville, OH, every bus driver and
his or her passengers had to endure SEVEN TIME CHANGES!
4. Congress finally got its act together and passed the Uniform Time
Act of 1966, which President Johnson signed into law on 13 April
1966. This mandated consistent application of DST within each
state participating in the program.
a. There are a couple of exceptions:
i. State legislatures were given the power to vote not to
participate in DST, and three have, perversely, done just
that: Arizona, Hawai'i, and Indiana (that's why they are
marked separately on the map of time zones I sent you to
earlier, oh, heck, here
is another link to it).
ii. Indiana changed its mind in 2006, so they now participate
in Daylight Savings.
iii. Also, if a state includes more than one time zone, its
legislature is free to allow the part in one time zone not
to participate, while voting that the other part has to
participate. Indiana did just that.
b. In 1986, Congress voted to change the date on which we start DST
from the last weekend in April to the first.
i. This extended the fuel-saving virtues of DST three weeks.
ii. So, the US was on Daylight Savings from the middle of the
FIRST weekend in April to the middle of the LAST weekend in
October.
c. In 2005, the Energy Policy Act changed the dates yet again, this
time both the beginning and the ending dates, effective 2007.
i. Daylight Savings now starts on the second Sunday in March.
ii. Daylight Savings now ends on the first Sunday in November.
iii. It's on the Saturday/Sunday midnight to let us
get used to the one hour "jet lag" it produces by Monday
(and to let the absent-minded ones among us find out we
blew it on Sunday, not on Monday, which has probably saved
more than a few people's jobs!).
d. During Daylight Savings, we all sort of pretend we live in the
next time zone east of us. So, that should tell you what to do
with the clocks:
i. Spring ahead (skip the clock ahead an hour on the first
weekend of April) and
ii. Fall behind (set the clock behind an hour on the last
weekend of October)
iii. Alternatively, I've heard it "spring forward and fall back"
5. Other countries participate in DST but, just to make the life of a
travel agent uncomfortable, each country switches at dates that may
differ from ours.
a. For example, the European Union runs DST from the last Sunday in
March through the last Sunday in October.
b. The Russians stay on Daylight Savings all year, but, during the
summer, they do double DST: They spring ahead and fall behind,
which leaves them two full hours apart from standard time!
C. The Date and the International Date Line.
1. By travelling far enough west, you begin to pick up more free time
than you're "entitled" to. Travelling from New York to Chicago,
you pick up one measly hour; flying from New York to Los Angeles,
you pick up three hours. Chump change so far. But imagine flying
from London to Anchorage, AK (135° of longitude between their
central meridians would be NINE full hours!).
2. Now imagine you fly from L.A. to New Zealand to Singapore to New
Delhi to Rome to London to New York and back to L.A.? Yep -- 24
hours of ill-gotten gain. This is an injustice crying for revenge,
wouldn't you say?
3. This is exactly what happened to Ferdinand Magellan's (Fernão de
Magelhães') crew in 1519-1522! He and his crew sailed from Seville,
Spain (he was a Portuguese Basque nobleman but felt he'd been aggrieved
by the King of Portugal and, so, to be a snot, he sailed under the
Spanish flag and the name Fernando Magellanes) on 10 August 1519.
a. This was an ill-starred, bloody expedition. You can read the
notes of one of the crew here.
b. Just some of their misfortunes:
i. Three of his ships' captains mutineed while overwintering
in Argentina, and he had two of them killed and the third
marooned (their drawn-and-quartered and impaled remains
were found nearly 60 years later by Sir Francis Drake, the
English pirate and Queen's spy, who got into the spirit of
things and had someone beheaded there for alleged mutiny,
too).
ii. Magellan's crews nearly starved and many died during the
long voyage west across an ocean that had looked so
peaceful after an awful passage through the Straits of
Magellan that Magellan named it the "Pacific."
iii. Magellan got himself killed in a battle he picked with one
of the peoples of one of the Philippine Islands, this on 28
April 1522 (Battle of Mactan).
c. The last 18 members of his crew of 237 on the last remaining
ship of the original five struggled back into port in Seville.
This ship had circumnavigated the world, conclusively proving it
was round. Magellan's crew did keep excellent records, and so
they were blown away by finding out it was the 8th of September,
1522, in Seville when they "knew" it "had to be" the 7th of
September.
d. This turned out to be a regular occurrence: You sail west
around the world, and it's going to be a day later than your
records show when you get back.
4. This is the problem eventually resolved by the International Date
Line. This is a designated spot where, if you cross that meridian,
you have to give back all those ill-got gains at once in one big
lump sum of 24 hours, a full day.
a. If you cross that line westbound, the hours have been getting
set back as you travel, but now you have to skip the calendar
ahead one full day.
b. Travelling eastbound across the line, you've been skipping the
clock as you travel along but now you get to set the calendar
day back so you can relive that whole day (hopefully more
happily than Magellan's crew did).
c. Crossing the International Date Line has the opposite effect of
crossing time zone boundaries, then, except it involves a whole
calendar day, not just a measly hour.
5. So, viewed spatially, there are TWO dates on the earth at any one
time. Only at noon, Greenwich Mean Time (12:00 UT) is there just
one date on Earth.
a. With our modern calendar, we change the dates at midnight, a
convenient hour in the wee hours, when all but a few night-owls
are asleep.
b. We can imagine the meridian experiencing noon and the antipodal
meridian experiencing midnight (and the change of date( as
chasing one another around the earth, passing over the fixed
meridians of the geographic grid. Let's say this is on, oh, the
1st of October.
c. As the midnight meridian sweeps across the earth past the
International Date Line, the new date of October 2nd begins and,
at first, covers only a narrow sliver of the earth. As the
midnight meridian continues, the slice of the new day gets wider
and wider and the slice of the old day gets skinnier and
skinnier until, once more, the midnight meridian passes directly
over the International Date Line and that new date, October 2nd,
is the only one left on Earth:
![[ the change of date on Earth ]](https://home.csulb.edu/~rodrigue/geog140/datesonearth.jpg)
D. And that concludes the lecture on the geographic grid, including
latitude, longitude, and time. You now have enough material to
complete Lab 1, available from the course home page.
Document and © maintained by Dr.
Rodrigue
First placed on web: 09/13/00
Last revised: 09/13/08