lesson 3 time hess, mcknight’s physical geography, 10 ed. pp. 21-24

Lesson 3Lesson 3Time

Hess, McKnight’s Physical Geography, 10 ed.

pp. 21-24

Local Sun TimeLocal Sun TimeTime can be measured by the

position of the sun in the sky“Noon” is when the sun is

directly overheadThis is known as zenith, when the

sun is at the highest point in the sky

Local Sun Time, cont.Local Sun Time, cont.

Problem 1Problem 1Problem: 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 TimeStandard TimeTo 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.

Time Zone CalculationsTime Zone CalculationsStandard time: 12:00 AM to 11:59 AM

12:00 PM to 11:59 PMMilitary 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, Time Zone Calculations, cont.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, Time Zone Calculations, cont.cont. UTC GMT EDT EST

CDTCST

MDTMST 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, Time Zone Calculations, cont.cont.

International Date LineInternational Date LineLocated 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, International Date Line, cont.cont.

Daylight Savings TimeDaylight Savings TimeUsed 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 Sunrise/Sunset Time CorrectionsCorrections

Lesson 4Lesson 4Map Scale

Hess, McKnight’s Physical Geography, 10 ed.

pp. 27-30

Graphic ScalesGraphic ScalesThe distance on a map related to

ground distanceLength on a map can be compared to

the graphic scale to find true ground distance

Remains accurate if the map is reduced/enlarged

Fractional ScalesFractional ScalesMap 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 rulerIf map scale is enlarged or reduced,

fractional scales will be inaccurate.

Fractional Scales, cont.Fractional Scales, cont.

Large Scale vs. Small Large Scale vs. Small ScaleScaleMany people think of this

backwards…Large scale maps show a small

area of Earth in great detailSmall scale maps show a large

area in less detail

Large or small scale?

HomeworkHomeworkLesson 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

lesson 3 time hess, mcknight’s physical geography, 10 ed. pp. 21-24

Documents