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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: - PowerPoint PPT Presentation
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Office HoursTue: 12:30 PM to 2:30 PMWed: 9:00 AM to 10:30 AM & 12:00 PM to 2:00 PMThr: 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/
Lesson 10Earth-Sun Relationships
Hess, McKnight’s Physical Geography, 10 ed.
15-21 pp.
Terms to KnowRotation: Earth completes one
rotation every 24 hours giving us day and night.
Terms, cont.Revolution: Earth completes one
revolution around the sun every 365 ¼ days.
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
Perihelion and Aphelion, cont.
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
Terms, cont.Inclination: Relative to the ecliptic
plane, Earth is tilted 23.5° from vertical at all times.
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!
Earth’s EquinoxesEquinox: 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.
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.
Sun’s Rays during Equinoxes
Sun’s Rays during Summer Solstice
Sun’s Rays during Winter Solstice
Video on Seasonshttp://
www.youtube.com/watch?v=taHTA7S_JGk
Powers of ten:◦http://youtu.be/vRjGarICal4◦http://youtu.be/0fKBhvDjuy0