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Lesson 3

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.

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Lesson 3

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  1. Lesson 3 Time Hess, McKnight’s 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: 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

  11. 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

  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 it’s the next day (+1 day) • If you cross the IDL from west to east, then it’s 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, McKnight’s 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 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.

  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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