UNIT 2 Earth Dimensions

1. UNIT 2 Earth Dimensions

2. A. Earth’s Shape: For thousands of years, many people thought Earth was flat. We now know that Earth is round, or to be more precise, a: sphere

3. What evidence do we have of Earth’s shape? Earth casts a round shadow during lunar eclipse   Movement of the stars/no movement of Polaris  Tops of distant objects appear first Photos from space

4. Actually, Earth is not a perfect sphere. Its shape is actually an: oblate spheroid Circumference of Earth at the equator is 40,076 km (24,902 mi.) and its diameter is 12,757 km (7,927 mi.). Circumference of Earth through the poles is 40,008 km (24,860 mi.) and diameter is 12,714 km (7,900 mi.).

5. Therefore, Earth seems to bulge outward a little at the equator and seems a flattened at the poles. What do we know about Earth that would cause it to bulge a little at the equator? Earth rotates (spins) and it rotates at a faster rate at the equator, causing Earth to bulge outward there.

6. Let’s extrapolate a little, shall we? Jupiter rotates once in about 10 hours. Would Jupiter be more oblate, less oblate, or just as oblate as Earth and why? It would be more oblate because it rotates faster than Earth. (10 hours vs 24 hours) or 2.4 times faster. This would cause the area of its equator to bulge outward even more than Earth’s.

7. Even though Earth is not perfectly spherical, the difference is so small that it appears to be perfectly round from all angles.

8. One little interesting fact that can help prove that Earth is slightly out of round is the fact that a person will weigh a little bit more at the poles than they do at the equator. This is because the force of gravity is greater the closer you are to the center of a large body of matter. Because you are slightly closer to the center of Earth at the poles, you will weigh slightly more.

9. B. Earth’s Sphere’s Earth outermost regions can be divided into three major areas or spheres. They differ from each other in composition and, very importantly, in density.  1. Atmosphere: shell of gases that surround Earth, extends outward several hundred kms, but still very thin; the least dense of Earth’s three spheres

10. The atmosphere is subdivided into layers. A. Troposphere: Lowest layer of the atmosphere; contains most of the atmosphere’s gases including oxygen and water vapor; weather occurs here B. Stratosphere. Layer above the troposphere; ozone layers occurs here; temperature increases with altitude

11. Mesosphere. Portion of the atmosphere from about 30 to 80 kilometers with temperatures ranging from about 10 to -90 degrees Celsius as you go up. Thermosphere. Outermost layer of the atmosphere. Aurora Borealis (Northern Lights) occurs here.

12. 2. Hydrosphere- This is the name for the waters that cover Earth on over 70% of its surface. “Hydro-” = water. Very thin compared to other spheres, averaging 3.5 – 4 km thick. Includes oceans, lakes, rivers, etc.

13. Hydrosphere - This is the name for the waters that cover Earth on over 70% of its surface. “Hydro-” = water. Very thin compared to other spheres, averaging 3.5 – 4 km thick. Includes oceans, lakes, rivers, etc.

14. Lithosphere: The most solid portion of Earth. It is also the most dense. It extends downward from surface of Earth from 70 – 150 km. Consists of rock and soil under our feet. It is what makes up our mountains, valleys and plains, even the ones under the oceans.

15. Earth’s Positions Coordinate System. Series of imaginary intersecting lines and points called coordinates to locate your position on Earth.

17. The coordinate system used most often and the one we will use, is called the: Latitude-longitude system The imaginary lines used in the latitude-longitude coordinate system are called: Parallels for latitude and meridians for longitude.

18. Latitude is a measure of a location’s angular distance north or south of the equator. All points on the surface of Earth that are the same distance from the equator lie along an imaginary line that is parallel to the equator. That’s how they got their name, “parallels”.

21. In the northern hemisphere, it is relatively easy to determine your latitude if you can see Polaris, the North Star. The position of Polaris in space is almost exactly over the geographic North Pole. Because of this, the altitude of Polaris as observed from your location is almost exactly identical to your latitude.

23. Longitude is a measure of an angular distance east or west from an imaginary line called the: __________________. • A meridian of longitude is any semicircle on Earth’s surface connecting the north and south poles. The meridian that passes through Greenwich, England has been designated the Prime Meridian. Hey, it had to be somewhere!!

24. Both latitude and longitude are measured in: Degrees These can be broken down into ______________ and further subdivided into ______________.

25. Both latitude and longitude are measured in: Degrees These can be broken down into minutes and further subdivided into seconds.

26. Both latitude and longitude are measured in: Degrees These can be broken down into minutes and further subdivided into seconds. There are ___________________ in each degree and _____________________ in every minute.

27. Both latitude and longitude are measured in: Degrees These can be broken down into minutes and further subdivided into seconds. There are 60 minutes in each degree and 60 seconds in every minute.

28. Latitude is measured in degrees north or south of the equator. The _____________ is at 0o, the __________________ is at 90 o north and the _________________ is at 90 o south.

29. Latitude is measured in degrees north or south of the equator. The equator is at 0o, the North pole is at 90 o north and the _________________ is at 90 o south.

30. Latitude is measured in degrees north or south of the equator. The equator is at 0o, the North Pole is at 90 o north and the South Pole is at 90 o south.

31. 0 degrees Longitude =Prime Meridian • 180 degrees Longitude = IDL (International Date Line)