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Earth-Sun Relationships p.p. 481 – 482 & 622 - 625. Nearly all energy that drives our weather and climate on Earth comes from the Sun Earth only absorbs less than one two billionth of this energy (0.000000002)
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Earth-Sun Relationships p.p. 481 – 482 & 622 - 625 • Nearly all energy that drives our weather and climate on Earth comes from the Sun • Earth only absorbs less than one two billionth of this energy (0.000000002) • Seems small, but it is several hundred thousand times the electrical-generating capacity of the U.S.
Solar energy is NOT distributed evenly over Earth’s surface. This varies due to: • Latitude • Time of day • Season of year
This causes unequal heating of the earth’s surface. The heat will try to balance, reach equilibrium. It is the unequal heating of the Earth that creates ___winds__ and drives the ocean’s _currents__ • These movements transport heat from the tropics towards the _Poles__ in an attempt to balance energy differences. • This is “WEATHER”
Earth’s Motions • Rotation - The turn of the Earth on it’s axis. Equals 24 hr./1 day • Revolution - The movement of the Earth around the Sun. Equals 365 days/1 yr.
Solar Day vs. Sidereal Day From one “noon” to the next. When the Sun reaches it’s Zenith About 24 hr. Noon occurs 4 min. earlier each day. After 6 months, “noon” occurs at midnight
Complete Exercise 12- Demonstrating the effect that sun angle has on the amount of solar radiation a place receives
Earth’s Orientation • Seasonal changes occur because Earth’s position relative to the Sun ___continually changes___ as it travels along the orbit. • The result of the above motions and a 23½ o inclination (tilt) is the reason • for ________seasons____. • Because of this inclination (tilt) it changes the angle of the Sun’s rays and the length of hours of daylight. This results in our seasons.
Solstices and Equinoxes • Summer Solstice (longest daylight of the year) • a. Occurs June _21_ or __22___. • b. Official first day of _summer_. • c. Sun’s vertical rays are located at the tropic of _Cancer_ which is 23 1/2o North latitude. • Winter Solstice (shortest daylight of the year) • a. Occurs Dec. _21_ or __22_. • b. Official first day of ___winter__. • c. Sun’s vertical rays at located at the Tropic of __Capricorn_ at 23 1/2o South latitude.
Autumnal equinox (equal hours of daylight and darkness) • a. Occurs Sept. _22_ or _23_. • b. Official first day of ___Fall or Autumn__. • c. Sun’s vertical rays are located at the ___equator____. • Spring equinox (equal hours of daylight and darkness) • a. Occurs March _21_ or __22_. • b. Official first day of ____spring__. • c. Sun’s vertical rays are located at the ___equator____.
Length of Daylight • 1. The length of daylight is determined by __Earth’s position in orbit__. • 2. The farther you are north of the equator on the summer solstice, the longer __period of daylight_. • 3. At the North Pole (June 21st) the length of daylight is ___24 hr.__. • 4. At the South Pole (June 21st) the length of daylight is ___0, it’s dark 24 hr. a day_.