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Time

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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
    find the day/time in Ecuador

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
    166 of your lab manual
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