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### Lesson 3 Time Hess, McKnight s Physical Geography, 10 ed. pp. 21-24 At a latitude of 40N 2011 Equinox, Sept 23 * * Local Sun Time Time can be measured by the ... – PowerPoint PPT presentation

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Title: Time

1
Lesson 3
• Time
• Hess, McKnights Physical Geography, 10 ed.
• pp. 21-24

2
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

3
Local Sun Time, cont.
4
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

5
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

6
Standard Time, cont.
7
Standard Time, cont.
•

8
Standard Time, cont.
9
Standard Time, cont.
10
Time Zone Calculations
• Standard time 1200 AM to 1159 AM
• 1200 PM to 1159 PM
• Military time/24-hour clock 0000 to 2359
• No AM or PM is needed
• Regular time and military timehow do you
convert?
• If its before 100 PM, no need to convert
• If its 100 PM or later, 12 to get military
time
• e.g., 101 PM 12 1301 military time
• 650 PM 12 1850

11
Time Zone Calculations, cont.
• Greenwich Mean Time (GMT)
• Runs through Greenwich, UKrecall 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

12
Time Zone Calculations, cont.
13
Time Zone Calculations, cont.
•

14
International Date Line
• Located in the middle of the Pacific Ocean near
180 longitude.
• If you cross the IDL from east to west, then its
the next day (1 day)
• If you cross the IDL from west to east, then its
the previous day (-1 day)

15
International Date Line, cont.
•

16
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

17
Sunrise/Sunset Time Corrections
•

18
Sunrise/Sunset Time Corrections
•

19
Lesson 4
• Map Scale
• Hess, McKnights Physical Geography, 10 ed.
• pp. 27-30

20
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

21
Fractional Scales
• Map distance related to true ground distance in
the form of a fraction or ratio
• e.g. 1/24,000 or 124,000
• 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.

22
Fractional Scales, cont.
•

23
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

24
• Large or small scale?

25
• large

26
• Large or small scale?

27
• small

28
• Large or small scale?

29
• small

30
• Large or small scale?

31
• large

32
Homework
• Lesson 4, Part 1, Q5 Skip this question. There
is no graphic scale listed on Map T-1
• Lesson 4, Part 1, Q6 Map T-9 can be found on pg