Lab # _____ Reading Daily and International Time Zone Maps
Introduction:
A 'Time Zone' generally refers to any of the 24 regions of the Earth’s surface, loosely divided by longitude, in
which standard time is kept. Time zones exist because the earth rotates counterclockwise (from east to
west). Therefore, when comparing any 2 locations, the region in the east will observe a later clock time than
the west because the sun will rise there first. Compare New York and California for example, the state that is
further east, New York, will experience sunrise and sunset before California. Therefore, it will always be later
in New York than in California. However, the number of standard time zones is debatable and discussed
among various sources, particularly with regards to the International Date Line. It is important to note that
some countries have non-standard time zones, usually with a 30-minute offset (some have a 45-minute
offset). For example, India maintains a time zone of five hours and 30 minutes ahead of Coordinated
Universal Time (UTC+5:30).
The Greenwich Meridian, also known as the prime meridian or International Meridian, bisects the primary
division of time zones. This is the starting point for longitude, with a measure of 0o. Any location to the right
of the Prime meridian is an Eastern measurement, while left of the Prime Meridian is a Western measure.
The International dateline, measuring 180o, is the line where the two meet on the opposite side of the globe.
Each time zone is 15 degrees of longitude in width, with local variations, and observes a clock time one hour
earlier than the zone immediately to the east. In summary, we add 1 hour for every time zone we count to
the right of a specified location, and subtract 1 hour for each time zone to the left.
Time zones’ boundaries are irregular mainly because of political factors, and so this has been a subject of
criticism. Time zones can be determined by how countries’ and states’ borders are positioned. Individual zone
boundaries are not straight because they are adjusted for the convenience and desires of local populations,
these lines zigzag around borders. Moreover, some geographically large countries, such as India and China,
use only one time zone but other large countries, such as Russia and the United States, have more than one
time zone.
Purpose: To interpret a time zone map of the United states and determine the time and date using
aninternational map.
Procedures:
A. Using the time zone map fo the United States (Map A) complete Data Table A to indicate the time at
each location based on the indivual time zone.
B. Complete Table B using the latitude-longitude map of the world and the data provided below:
1. When it is 8 am Sunday at 15o E, identify the time and day at 90o W
2. What is the time and day at 120o E when it is 11am Saturday at 75o W
3. When it is 4pm July 4th in Denver Colorado (105o W), what is the time and date in Sydney,
Austrailia (150o E)
4. When it is noon on June 21 in New York City (75o W), what is the hour and date at:
a. 120o E
b. 120o W
c. 15o E
d. 15o W
e. 165o E
f. 75o E
5. If it is 9am on Tuesday in San Francisco, Ca (120o W), what is the hour and date at:
a. Sydney Australia (150o E)
b. Moscow (30o E)
Data Table #1
City
Time A
Atlanta, GA
12 noon
Boise, ID
Chicago, IL
Juneau, Ak
Honolulu, HI
Los Angeles, CA
New York, NY
San Antonio, TX
Seattle, WA
Time B
1:00 AM
6:30 PM
Data Table #2
Given City
Name/Longitude Time
1
2
3
4
4a
4b
4c
4d
4e
4f
5a
5b
Time C
City in Question
Day/Date
Name/Longitude Time
Day/Date
Questions:
1. What is the earth’s rate of rotation?______________________
2. How many different time zones are there in the United States? (see map A)____________________.
3. How are the time zone lines in the United States determined? (Identify two factors that influence the
placement of the lines.)_______________________________________________________________
4. What are the names of the time zones in the continental United States?_________________________
______________________________________________________________________________________
5. List the pairs of cities (from your data table #1) that are in the same time zone in the Untied States.
___________________________ ___________________________ ___________________________
6. For which time column in data table #1 (A, B, or C) do some cities have differnet dates as well as
different times? Explain. _____ ________________________________________________________
___________________________________________________________________________________
7. Clocks in Detroit and Boston are both set to Eastern Standard Time. In which of these two citites
would the sun rise later (by clock time)?__________________________________________________
8. Draw an arrow from Bismark ND to Dallas TX . Draw a second arrow from Bismarck ND to Seattle WA.
Does the distance between tow cities help you predict whether they are in the same time zone?
Explain.____________________________________________________________________________
9. What is the purpose of the international dale line zig zag?____________________________________
___________________________________________________________________________________
10. How does the date change when a ship crosses the international date line giong:
a. Eastward __________________________
b. westward______________________________
11. At what time would a plane arrive in Denver 105o W after a four hour flight from NYC 75o W which
began at 5 pm Eastern Standard time? ___________________________________________________
World Map