FALL HAS BEGUN...It shows itself in different ways around mother earth. The seasons are a powerful force in our lives. They affect the activities we do, the foods we crave, the clothes we wear — and quite often, the moods we are in. The seasons officially change once again on Sunday, with autumn beginning in the Northern Hemisphere and spring starting in the south. What is it that causes the change in seasons? The ability to predict the seasons — by tracking the rising and setting points of the sun throughout the year — was key to survival in ancient times. The Babylonians, the Maya and other cultures developed complex systems for monitoring seasonal shifts. But it took centuries more to unravel the science behind the seasons. Solstices and equinoxes The seasons are marked by solstices and equinoxes — astronomical terms that relate to Earth’s tilt. At the same time that the Northern Hemisphere is entering summer, the South Pole is tilted away from the sun, and the Southern Hemisphere is starting to feel the cold of winter. The sun’s glancing rays are spread over a greater surface area and must travel through more of the atmosphere before reaching the earth. There are also fewer hours of daylight in a 24-hour period. The situations are reversed in December, when it’s the Southern Hemisphere that basks in the most direct rays of the sun, while the Northern Hemisphere receives less dense solar radiation for shorter periods of time.
Posted on: Mon, 23 Sep 2013 06:30:55 +0000
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