1 / 15

# Office Hours

Office Hours. Tue: 12:30 PM to 2:30 PM Wed: 9:00 AM to 10:30 AM &amp; 12:00 PM to 2:00 PM Thr : 9:00 AM to 10:30 AM Course Syllabus can be found at: http://www.wx4sno.com/portfolio/BSU/Fall_2011 / This lecture will be posted AFTER class at:

## Office Hours

E N D

### Presentation Transcript

1. Office Hours Tue: 12:30 PM to 2:30 PM Wed: 9:00 AM to 10:30 AM & 12:00 PM to 2:00 PM Thr: 9:00 AM to 10:30 AM Course Syllabus can be found at: http://www.wx4sno.com/portfolio/BSU/Fall_2011/ This lecture will be posted AFTER class at: http://www.wx4sno.com/portfolio/BSU/Fall_2011/Lectures/

2. Lesson 10 Earth-Sun Relationships Hess, McKnight’s Physical Geography, 10 ed. 15-21 pp.

3. Terms to Know • Rotation: Earth completes one rotation every 24 hours giving us day and night.

4. Terms, cont. • Revolution: Earth completes one revolution around the sun every 365 ¼ days.

5. Terms, cont. • Revolution is not a perfect circle, more of an elliptic. • When revolution brings earth closest to sun: perihelion • When revolution takes earth furthest from sun: aphelion Point 1: Earth at aphelion Point 2: Earth at perihelion Point 3: Sun

6. Perihelion and Aphelion, cont.

7. Terms, cont. • Ecliptic plane: This is the level, or plane, of Earth’s orbit around the sun…Earth’s orbital path. • Astronomically, this is the primary plane referred to when discussing the revolution of other planets around the sun

8. Terms, cont. • Inclination: Relative to the ecliptic plane, Earth is tilted 23.5° from vertical at all times.

9. Terms, cont. • Polarity: Because Earth is always tilted 23.5°, it’s axis is always pointed in the same direction…towards the star Polaris. • Because of this regular tilt, when the Earth revolves around the sun, the North pole is either tilted towards the sun (June) or tilted away from the sun (December) • DO NOT confuse this with Earth’s magnetic field!

10. Earth’s Equinoxes • Equinox: Earth is positioned so that its is neither towards nor away from the sun…giving the entire planet equal amounts of day and night. • Occurs twice each year, around March 20 and September 22.

11. Earth’s Solstices • Solstice: Earth is positioned where its tilt is either towards or away from the sun. • Occurs twice a year, just like the Equinoxes, around June 21 and December 21. • The direct rays from the sun hit the earth at 23.5°N on June 21, while the tangent rays hit the earth around 66.5°N and 66.5°S.

12. Sun’s Rays during Equinoxes

13. Sun’s Rays during Summer Solstice

14. Sun’s Rays during Winter Solstice

15. Video on Seasons • http://www.youtube.com/watch?v=taHTA7S_JGk • Powers of ten: • http://youtu.be/vRjGarICal4 • http://youtu.be/0fKBhvDjuy0

More Related