Lesson 3
Time
Hess, McKnight’s Physical Geography, 10 ed.
pp. 21-24
Local Sun Time
Time can be measured by the position of
the sun in the sky
 “Noon” is when the sun is directly
overhead

 This is known as zenith, when the sun is at the
highest point in the sky
Local Sun Time, cont.
Problem 1

Problem: If it is noon where you are, would it
be before or after noon for someone that is
east of you?
◦ After noon

Recall, the sun rises in the east and sets in the
west
◦ As you look down from the north pole, the earth
would rotate counterclockwise
◦ If the sun is just beginning to rise in California, then
the sun would be near noon in New York, so…
◦ As you travel east, time becomes later
Standard Time
To simplify things, 24 zones of standard
time have been established internationally
 As you move from one time zone to the
next adjacent time zone, standard time
changes by one hour

Standard Time, cont.
Standard Time, cont.

Standard Time, cont.
Standard Time, cont.
Time Zone Calculations
Standard time: 12:00 AM to 11:59 AM
12:00 PM to 11:59 PM
 Military time/24-hour clock: 00:00 to 23:59

◦ No AM or PM is needed

Regular time and military time…how do you
convert?
◦ If it’s before 1:00 PM, no need to convert
◦ If it’s 1:00 PM or later, +12 to get military time
 e.g., 1:01 PM + 12 = 13:01 military time
6:50 PM + 12 = 18:50
Time Zone Calculations, cont.

Greenwich Mean Time (GMT):
◦ Runs through Greenwich, UK…recall which is
0° longitude
◦ Established in 1884 (height of British naval
dominance)
◦ 24-hour clock known today as the Universal
Time Coordinate (UTC) or Zulu time
◦ Used as a reference
 If you know the current UTC time, you can figure
out what time it is anywhere in the world
Time Zone Calculations, cont.
UTC GMT
EDT
EST
CDT
CST
MDT
MST
PDT
PST
0000
2000
1900
1800
1700
1600
0100
2100
2000
1900
1800
1700
0200
2200
2100
2000
1900
1800
0300
2300
2200
2100
2000
1900
0400
0000
2300
2200
2100
2000
0500
0100
0000
2300
2200
2100
0600
0200
0100
0000
2300
2200
0700
0300
0200
0100
0000
2300
0800
0400
0300
0200
0100
0000
0900
0500
0400
0300
0200
0100
1000
0600
0500
0400
0300
0200
1100
0700
0600
0500
0400
0300
1200
0800
0700
0600
0500
0400
1300
0900
0800
0700
0600
0500
1400
1000
0900
0800
0700
0600
1500
1100
1000
0900
0800
0700
1600
1200
1100
1000
0900
0800
1700
1300
1200
1100
1000
0900
1800
1400
1300
1200
1100
1000
1900
1500
1400
1300
1200
1100
2000
1600
1500
1400
1300
1200
2100
1700
1600
1500
1400
1300
2200
1800
1700
1600
1500
1400
2300
1900
1800
1700
1600
1500
Time Zone Calculations, cont.

International Date Line
Located in the middle of the Pacific
Ocean near 180° longitude.
 If you cross the IDL from east to west,
then it’s the next day (+1 day)
 If you cross the IDL from west to east,
then it’s the previous day (-1 day)

International Date Line, cont.

Daylight Savings Time
Used primarily in the U.S. to add an
“extra” hour of daylight in the afternoon
during spring/summer
 Just remember, “Spring forward and Fall
back”
 Problem Part I, question 4:

◦ Convert daylight savings time in KC to
standard time by subtracting one hour, then
continue to find the day/time in Ecuador
Sunrise/Sunset Time Corrections

Sunrise/Sunset Time Corrections

Lesson 4
Map Scale
Hess, McKnight’s Physical Geography, 10 ed.
pp. 27-30
Graphic Scales
The distance on a map related to ground
distance
 Length on a map can be compared to the
graphic scale to find true ground distance
 Remains accurate if the map is
reduced/enlarged

Fractional Scales

Map distance related to true ground distance in
the form of a fraction or ratio
◦ e.g. 1/24,000 or 1:24,000
 This is to say that “one unit on the map is equal to 24,000
units on the ground”
Need a calculator and ruler
 If map scale is enlarged or reduced, fractional
scales will be inaccurate.

Fractional Scales, cont.

Large Scale vs. Small Scale
Many people think of this backwards…
 Large scale maps show a small area of
Earth in great detail
 Small scale maps show a large area in less
detail

Large or small scale?
large
Large or small scale?
small
Large or small scale?
small
Large or small scale?
large
Homework
Lesson 4, Part 1, Q5: Skip this question.
There is no graphic scale listed on Map T1
 Lesson 4, Part 1, Q6: Map T-9 can be
found on pg 166 of your lab manual
