the reason for the seasons - university of chicagomath.uchicago.edu/~grodnick/seasons.pdfafter...
TRANSCRIPT
The Reason for the Seasons
SESAME AstronomyWeek 1 - January 12th, 2010
Thursday, January 13, 2011
the year
takes 1 day for earth to make 1 rotation (to rotate once) on its axis
takes 1 year for earth to make 1 complete orbit (revolution)
rotation axis tilted with respect to orbit
rotation axis tilted in the same direction with respect to the background stars, no matter where in orbit earth is
Huh?Thursday, January 13, 2011
the year
takes 1 day for earth to make 1 rotation (to rotate once) on its axis
takes 1 year for earth to make 1 complete orbit (revolution)
rotation axis tilted with respect to orbit
rotation axis tilted in the same direction with respect to the background stars, no matter where in orbit earth is
Huh?
Thursday, January 13, 2011
Thursday, January 13, 2011
direct vs. indirect light
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Thursday, January 13, 2011
Thursday, January 13, 2011
Thursday, January 13, 2011
Thursday, January 13, 2011
Thursday, January 13, 2011
Thursday, January 13, 2011
Summer solstice - June 21stlongest day of yearsun as high as it gets in the skyEarth tilted toward sun
Winter solstice - December 21stshortest day of the year sun as low as it gets in the skyEarth tilted away from sun
Equinoxes - March 21st/September 21stequal number of hours of light and darkelevation of sun at noon equal to latitudeEarth tilted neither toward or away from sun
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So why is the winter solstice near the
beginning of winter, and not the middle of
winter?
Thursday, January 13, 2011
There’s A LOT of water!
Water takes a long time to cool off
As the water cools off, it warms up the air (so air stays warm longer than sunlight can account for)
Water takes a long time to heat up
As the water heats up, it cools off the air (so air stays cool longer than sunlight can account for)
After summer solstice After winter solstice
Thursday, January 13, 2011
Activities
Play with computer demos
Do sunrise/sunset activity
Come back for summation and discussion of homework and projects
Thursday, January 13, 2011
Summary
Earth rotates on an axis once per day
This axis is tilted with respect to Earth’s orbit around the sun
When the Earth is tilted toward the sun, sunlight is “direct” (meaning: more concentrated)
This concentrated sunlight heats up the part of Earth tilted toward the sun
Thursday, January 13, 2011
Summary
As the Earth moves around its orbit, the tilt faces away from the sun
When the Earth is tilted away from the sun, sunlight is “indirect” (meaning: watered down)
This watered down sunlight can’t keep the Earth warm, and the part of Earth tilted away from the sun cools off
Thursday, January 13, 2011
Summary
June 21st: summer solstice - most sunlight
June 22nd: Earth moves away from summer solstice
July-August: Earth still moving away from summer solstice, but water cools off and warms up air at same time to keep Earth warm through summer
December 21st: winter solstice - least sunlight
December 22nd: Earth moves away from winter solstice
January-February: Earth still moving toward summer solstice, but water warms up and cools air at the same time to keep Earth cool through winter
Thursday, January 13, 2011
AssignmentsRead through http://www.astronomy.org/programs/seasons/
This website gives 2 common misconceptions about why we have seasons. For each misconception, imagine that one your students made that claim. Write what your response to the student would be. Please type your assignments. (You may draw diagrams, though.)
Finish worksheets started in class
Start sun project and moon project - have ready for project checks next Wednesday
Thursday, January 13, 2011
Resources
http://www.astronomy.org/programs/seasons/
Thursday, January 13, 2011