BIOLOGY 2F03 Chapter : Biology 2F03.pdf
14 Dec 2013
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Document Summary
Uneven heating of the earth"s spherical surface by the sun and the tilt of the earth on its axis combine to produce predictable latitudinal variation in climate. Because the earth is a sphere, the sun"s rays are most concentrated where the sun is directly overhead which changes with seasons. Earth"s axis is tilted approximately 23. 5o away from the perpendicular. June 21st during summer solstice, the sun is directly overhead at the tropic of cancer, 23. 5o n latitude. December 21st during winter solstice, sun is directly overhead at tropic of capricorn, 23. 5os latitude. Sun is directly over the equator during the spring and autumnal equinoxes. Heating of the earth"s surface and atmosphere drives circulation of the atmosphere and influences patterns of precipitation. Air moving from 30o latitude back to the equator completes a thermal loop, which forms the hadley cell. Polar cell driven by ait movement associated with warming at 60o latitude and cooling at the poles.
