Motion of the Earth

1. Motion of the Earth Climates, Seasons, & Days

2. Earth’s Motion • Earth has two major types of motion: • Earth’s Rotation • Earth’s Revolution

3. Earth’s Rotation • The spinning of the Earth on its axis • the axis is the imaginary line that runs vertically through the center of the Earth • rotates from East to West (counterclockwise) • Rotation of the Earth produces 2 main effects: • Speed causes the length of a day to be about 24 hours • Causes daily changes from day to night • At all times half of the Earth faces the sun, while the other half is in darkness • Areas within the Artic & Antarctic circles experience several weeks of daylight or darkness depending on the time of year

4. Earth Rotating

5. Earth’s Revolution • The movement of Earth around the sun • Earth’s orbit is the slightly elliptical path that it travels around the sun • The sun is not in the center: • Around January 3rd earth is about 147million km away (closer) • Around July 4th earth is about 152 million km away (farther) • Revolution has 2 major effects: • The time it takes Earth to revolve around the sun once defines the length of a year • It takes 365 ¼days to make one complete revolution • Every 4th year is leap year to make up for the extra day we gained • Earth revolves with a tilt of the axis • The revolution & tilt causes the changing seasons

6. Earth’s Revolution

7. How Earth Moves • In your group, demonstrate the difference between a rotation & a revolution.

8. Changing Seasons • Earth’s axis is at an angle of 23.5° to its orbit • The axis always points in the SAME direction as the Earth orbits the Sun. • The Northern hemisphere points toward the sun half of the year & away from the sun for half the year • The tilt causes the Earth’s surface to receive different amounts of solar energy throughout the year.

9. Radiation from the Sun • The hemisphere that is tilted toward the sun receives more daylight hours and absorbs more radiation from the sun • The Sun’s radiation strikes the earth surface at a higher angle when the hemisphere is tilted toward the sun • The higher the angle the more radiation the earth absorbs creating warmer temperatures

10. Seasons on Earth • Which month is receiving the most direct sunlight? • Least direct amount

11. Solstices • A solstice is the day when the Sun reaches its greatest distance north or south of the equator • The day Earth is tilted most toward the sun • June 21st is the summer solstice (northern hemisphere) • The most direct rays hit the Tropic of Cancer in the northern hemisphere causing the northern hemisphere to have warmer temperatures and more sunlight hours • Longest day of sunlight for the year • Daylight gets a little shorter each day after the solstice • Dec. 21st is the winter solstice (northern hemisphere) • The most direct rays hit the Tropic of Capricorn in the southern hemisphere causing the northern hemisphere to have cooler temperatures and less sunlight hours • Shortest day of sunlight for the year • Daylight hours get a little longer each day after the solstice

12. Equinox • An equinox is the day the Sun’s rays are directly above the Earth’s equator. • During this time equal amounts of sunlight are received all over the earth with the most direct rays hitting at 90° at the equator • March 21st is the spring equinox (northern hemisphere) • September 22nd is the autumn equinox (northern hemisphere) • Seasons are opposites in the Southern Hemisphere

13. Seasons on Earth • Earth has seasons because it is tilted as it revolvesaround the sun.

14. No matter what time of year, which areas of Earth receive the least direct sunlight?

15. Animation • revolution • Revolution • Extra Practice • Click on view

16. Climatic Zones • The amount & angle of sunlight affects Climatic Zones • The latitude, distance north or south from the equator, affects the temperatures that commonly occur in that area. • The further from the equator the less direct the suns rays are • These yearly patterns cause weather patterns to occur in different regions of the earth that create climates.

17. World Climate Zones: Label in notes • Based on latitude, Earth’s surface can be divided into a tropical zone, two temperate zones, and two polar zones.

18. World Climate Zones • Polar Zone: Areas within the Arctic and Antarctic Circles, from 66.50Nand Slatitude to the poles • Characterized by a short, cool summer and long, bitterly cold winter. • Temperate Zone: between 23.50and 66.50north and south latitudes • warm to hot summers and cool winters • Greatest temperature variation • Tropic Zone: 23.50 degrees north latitude to 23.50 south latitude • Warm year round with little seasonal variation

19. Air Temperature by Month

20. Biomesare large geographical areas with similar climates and ecosystems