Unit 4: Sun-Earth Relationships. Revolution Rotation Declination (Tilt of Earth’s Axis) Seasons Time Zones Insolation and its variation. Sunrise over the Earth. Source: http://ajorbahman.blogspot.com/2011/02/third-of-russians-think-sun-spins-round.html. OBJECTIVES
Sunrise over the Earth. Source: http://ajorbahman.blogspot.com/2011/02/third-of-russians-think-sun-spins-round.html
Earth revolves around the Sun in an elliptical path. Earth and Sun are not drawn to scale, and the orbit’s elongation is highly exaggerated for clarity.
Video shows misconceptions about the cause of the seasons. http://www.youtube.com/watch?v=iMEfYLvxioc
Midnight Sun: Within the Arctic and Antarctic Circle the Sun does not set at Summer Solstice
Why are the boundaries not straight lines?
Why are the Prime Meridian, International Dateline significant?
Reception of solar radiation at different latitudes showing direct, indirect rays
Daylength (left axis) and noon solar altitude (right axis) at 45° north latitude. These factors work together in producing pronounced seasonality at middle and high latitudes. Notice also how the pace of change in both is much greater near the equinoxes than near the depths of summer and winter.
Spatial distribution of insolation at top of the atmosphere as percentage of global average
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Seasonal and spatial variation in solar radiation reaching the top of the atmosphere as a percentage of the global average. The latitude axis is scaled to acount for shrinking area at higher latitudes. Compare with patterns of the previous figures to see how solar position modulates the effect of daylength.