Earth Seasons by liaoqinmei

VIEWS: 2 PAGES: 12

									     “A Globe Walk”
      Modeling the
“Reasons for the Seasons”
   “Models are tentative schemes or
structures that correspond to real
objects, events, or classes of events,
and that have explanatory power…….”
The National Science Education
Standards (Page 117); National
Academy Press 1998.
           A Class of Events
• Earth Rotates on Its Axis
• Earth is Tilted on its Axis
• Earth’s Revolves in an Orbit around the Sun
• Earth’s Orbital Radius is Constantly
  Changing.
• The Lengths of Daytimes Gradually Change
  as the Seasons Change.
• The Altitudes of the Sun Gradually Change
  during a Day and as the Seasons Change.
• Seasonal changes are most dramatic in the
  Polar Regions.
Most students are aware of seasonal changes in lengths of
 daytime but may not know that they depend on Latitude.




   http://www.eoearth.org/article/Earth-Sun_relationships_and_insolation
            Students are probably less aware of
        seasonal changes in the “altitude” of the sun.
       Today, the “midday” altitude of the sun in Kotzebue,
      Alaska is 44.8º at 1:55 PM Alaska Standard Time.




The Distant Horizon


                      A U.S. Naval Observatory web site provides
                      the sun’s altitude on any day at any Latitude
.
      http://www.usno.navy.mil/USNO/astronomical-applications/data-services/alt-az-us
Kotzebue, Alaska is located 33 miles
     north of the Arctic Circle




 You can learn more about Kotzebue
      by visiting their web site.
        http://kotzpdweb.tripod.com/city/index.html
    Today, the “midday” altitude of the sun in Amherst is
         69.4º at 11:50 AM Eastern Standard Time.




The Distant Horizon


                       A U.S. Naval Observatory web site provides
                       the sun’s altitude on any day at any Latitude
.
       http://www.usno.navy.mil/USNO/astronomical-applications/data-services/alt-az-us
 Diagrams have limited value illustrating
seasonal changes in the altitude of the sun
         and lengths of daytime




   http://okfirst.mesonet.org/train/meteorology/Seasons.html
   Animations can more effectively reveal
       aspects of seasonal changes
      such as the lengths of daytimes
           in the Polar Regions.



http://www.cs.sbcc.cc.ca.us/~physics/flash/LengthofDay.swf



   http://esminfo.prenhall.com/science/geoanimations/ani
               mations/01_EarthSun_E2.html
         The Globe Walk


  A classroom, a model of the sun, a
model of Earth, a representation of
Earth’s orbit, two straws, and a
protractor can be used to demonstrate
a variety of daily and seasonal
changes.
       A Demonstration of
     Solstices and Equinoxes

        The 2010 Astronomical Seasons
             (for the Northern Hemisphere)


  Spring began at 12:32 PM EST on March 20th
   Summer began at 6:28 AM EST on June 21st
Autumn will begin at 10:09 EST on September 21st\
Winter will begin at 6:38 PM EST on December 21st
       Other Globe Walk
     Demonstrations Include:
• Changes in the altitude of the sun at
  different Latitudes as the seasons
  change.
• Changes in the Lengths of Daytimes at
  different Latitudes as the seasons
  change.
• Summer Solstice at the North Pole.
• Daily changes in the Altitude of the Sun.

								
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