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Chapter 1 Introduction to Earth

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1 Chapter 1 Introduction to Earth
Physical Geography A Landscape Appreciation, 9/e Animation Edition Victoria O. Alapo, Instructor Geog 1150 – Weather & Climate

2 Introduction to Earth Geography as a Field of Learning
Geography is from two Greek words, “Geo” – Earth, and “Graphien” – to write. Elements/Branches of Geography – Physical & Human or Cultural (see next slide). This class is concerned with Physical Geography. Also, see pg 2 (Fig. 1-1a and b) for interesting info about Earth.

3 Elements of Geography Table 1-1 (pg 1) Interrelationships among elements

4 Introduction to Earth Environmental Spheres (next slide)
The Solar System Size and Shape of Earth The Geographic Grid Earth Movements Annual March of the Seasons Telling Time

5 Environmental Spheres
Lithosphere Litho, Greek for “stone” Atmosphere atmo, Greek for “air” Hydrosphere hydro, Greek for “water” Biosphere bio, Greek for “life”    L A H B Interacting spheres Figure 1-2

6 The Solar System Figure 1-6: “Elliptical” orbits – Pluto is NO longer one of the planets in our solar system as of 2006 (see page 8).

7 The Size and Shape of Earth
“3rd Rock from the Sun” (93 million miles) Size Diameter – approx. 8,000 miles (12,800 km) at the equator 5th largest in diameter Fig. 1-6 (cropped)

8 Size and Shape of Earth Figure 1-8
Earth’s highest pt: 29,000 ft above sea level. Lowest point: 36,000 ft below sea level More bulgy at the equator: a difference of 0.3%. As a result, it’s not a ‘true/perfect’ sphere (circle), but an “Oblate Spheroid”, slightly flat on top and bottom. Figure 1-8

9 Angle of Tilt See “imaginary rotation axis”.
Interesting fact about Earth: The Earth tilts towards the east, at an angle of 23.5 degrees. This is called the “inclination of the rotation axis”.

10 The Geographic Grid The Combination of Latitude and Longitude Lines

11 Summary (Geographic Grid)
Longitude (also called Meridians) Measures distance east and west around the globe, beginning at the Prime Meridian Important longitude lines: Prime Meridian & International Date Line 0-180 degrees East or West Latitude (also called Parallels) Location on the Earth’s surface between the equator and the north or south pole Important latitude line: Equator 0-90 degrees North or South

12 The Geographic Grid The Equator (next slide) – the line thru the earth’s middle Latitude (run north and south of Equator) Longitude – E/W of the Prime/Greenwich Meridian They are used to establish location, for navigation and for telling time. The circle is 360 degrees around; therefore since there are 24 MAJOR longitude lines, each line is 15 degrees, same as ONE HOUR. So 360 degrees = 24 hours.

13 The Equator More interesting facts about Earth:
Earth ALWAYS points to ‘Polaris’, the North Star (see pg 17 & 18) Earth moves/ rotates from West to East.

14 Great and Small Circles
A great circle is the largest circle than can be drawn on a sphere and they bisect the Earth into 2 equal halves e.g. 1. The Equator 2. The Prime Meridian 3. The Sun’s Circle of Illumination (see “Blue Beauty” NASA slides) Small circles are any other circles that can be drawn.

15 Latitude: Parallels There are 7 important parallels.
Measures from 0º to 90º N and S of the equator. Also, the “Tropics” or tropical areas are hotter, due to the ‘bulge’. See pg 12 – Tropic of Capricorn (Australia).

16 Longitude: Meridians See Greenwich Photos
0 degrees Longitude passes thru Greenwich, England. And it’s then measured East and West. Measures from 0º to 180º E & W of the Prime/Greenwich Meridian. See pg 14. Established in 1884 at the International Meridian Conference in Washington, D.C. Also used for determining World Time (every 15 degrees is an hr).

17 Regions on Earth (Latitude bands)
Low latitude » 0º – 30º N and S (close to Equator) Mid latitude » 30º – 60º N and S High latitude » 60º – 90º N and S (close to poles) Equatorial » within a few degrees of the equator Tropical » within the tropics between 23.5º N and 23.5º S Subtropical » 25º – 30º N and S Polar » within a few degrees of the North and South Pole

18 Earth Movements Rotation on Axis (Daily)
One complete rotation is 24 hrs Rotation Direction (West to East), see next slide Rotation Speed, see table and pg 15-16 Revolution Around Sun (Annual) 365 days, 5hrs, 48 minutes and 46 seconds, simplified to or 365 ¼ days Leap Year

19 Rotation Direction West to East

20 Rotation Speed Now Table 1-5 Note: Always constant speed,
only DISTANCE at each location varies!

21 Annual March of Seasons
Solstices – Summer & Winter; unequal daylight (see next slides) Equinoxes – 12 equal hours of daylight; start of Spring and Fall (anywhere between the 20th and the 23rd) Also, see Table 1-7 (pg 22)

22 Solstices

23 Equinoxes

24 Changes in Daylight

25 Time Zones Accurate calendars have been kept by great civilizations for 1000s of years – the Egyptians, Mayas, Aztecs, Chinese, Indians, etc. Pg 23 (Babylon – 2,000 B.C.) A.M. & P.M. are Latin words (pg 23). “Meri” (highest) is the root word for “Meritorious”. 3 units of natural time – the year, month and day. Everything else is man-made (hour, minute, second, etc)

26 Time Zones Standard Time – starts at the Greenwich Meridian (GMT) or ‘Zulu’. Now called UTC (Universal Time Coordinated). All areas to the east of the Prime Meridian are ‘ahead’ in time, and all areas to the west are ‘behind’ in time. Some countries have one time zone, while others have several. Russia has 9. International Date Line (further slides)

27 World Time Zones

28 U.S./Canada Time Zones

29 International Date Line
Starts at 180 degrees; this is also where a NEW DAY (new DATE) begins i.e. 12 Midnight. It is the OPPOSITE of the Prime Meridian (zero degrees longitude) in Greenwich i.e. 12 Noon There is a difference of 12 hours between the Prime Meridian (zero degrees) and the International Date Line (180 degrees longitude)

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