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Why We Have Seasons :. Seasons are caused by the 23.5 0 tilt of Earth combined with Earth’s revolution around the Sun Earth’s axis is always pointed in the same direction (fixed position). ~12 hrs. Equator. ~15hrs. Tropic of Cancer. ~9hrs. Tropic of Capricorn. Equator. ~12 hrs.
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Why We Have Seasons: • Seasons are caused by the 23.5 0 tilt of Earth combined with Earth’s revolution around the Sun • Earth’s axis is always pointed in the same direction (fixed position)
~12 hrs Equator ~15hrs Tropic of Cancer ~9hrs Tropic of Capricorn Equator ~12 hrs
24 hrs darkness 24 hrs daylight 24 hrs daylight 24 hrs darkness Why is there More Hrs of Daylight in Summer?
Summer Solstice • 1st day of Summer • June 20th or 21st (N.H.) • Day of the year with the most hrs of daylight (~15) • Sunlight is hitting Tropic of Cancer
Autumnal Equinox • 1st day of Fall • Sept 22nd or 23rd(N.H.) • Day of the year with about equal hrs of daylight (~12) • Sunlight is hitting Equator
Winter Solstice • 1st day of Winter • Dec 21st or 22nd (N.H.) • Day of the year with the least hrs of daylight (~9) • Sunlight is hitting Tropic of Capricorn
Vernal Equinox • 1st day of Spring • march 20th or 21st(N.H.) • Day of the year with about equal hrs of daylight (~12) • Sunlight is hitting Equator
Summer Solstice (15 hrs daylight) Hrs of daylight decrease Fall Equinox (12 hrs daylight) Hrs of daylight decrease Winter Solstice (9 hrs daylight) Hrs of daylight increase Vernal Equinox (12 hrs daylight) Hrs of daylight increase Summer Solstice (15 hrs daylight)
Seasons Animations: • http://projects.astro.illinois.edu/data/Seasons/seasons.html • http://esminfo.prenhall.com/science/geoanimations/animations/01_EarthSun_E2.html • http://astro.unl.edu/naap/motion1/animations/seasons_ecliptic.html Video clip Bill Nye Seasons Video clip #2