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3.Why do we have seasons

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Greetings! From the northern hemisphere. Where in a couple of weeks summer will officially begin. Well, our friends in Sydney, Johannesburg, and Beunos Aires, are getting ready for winter. But no matter where you are or when you are watching this, you are never more than three months away from the change of seasons. And who can be thanked for this? The sun partly, and the way the earth leans into it. So, the earth spins on its axis at a fixed angle of about 23 and one half degrees. And, as the earth goes around the sun once every 365.25 days, this axial tilt or obliquity changes the exposure of the sun's radiation to different parts of the earth to experience at any given time. So starting in a couple of weeks, the northern hemisphere will tilt towards the sun. And people will break out the ice tea and sun screen while the southern hemisphere will point away. and begin bundling up for the relative darkness of winter. But, here is the thing, lots of people think that the hemisphere that is tilted towards the sun, experiences sun because it's closer. And therefore hotter, which is just false. In fact, those of you in the northern hemisphere might be surprised to know that the earth is actually 5 million kilometers closer to the sun in January than it is in July. So the difference doesn't have to do with your hemisphere's proximity to the sun. It has to do with the angle of the sun's rays that it receives. Let's say that this piece of paper is the earth's surface. And this flashlight, is the light of the sun. When the light shines directly on to the paper at a right angle, you see a perfect illuminated circle. But when I tilt the flashlight, that circle stretches into a ellipse. So the same total amount of light is hitting the paper, but it's now more spread out. So the light energy per square centimeter is reduced. This effect combined with the fact that higher sun angles result in longer days, means that more energy is heating your hemisphere in the summer, and less in the winter. But if you are near the equator, you probably, barely notice any seasons at all since you get roughly the same amount of sun year around. The poles on the other hand feel the difference in a pretty big way. That 23.5 degree tilt ensures that they never point directly at the sun, but they still spend about half a year bathed in daylight and the other half in near total darkness. So the next time you are picking daffodils, getting a tan, carving pumpkins or building snowmen, take a second to think about, how you are leaning, towards or away from the sun. And enjoy the uniqueness of the season. If you get them!

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Duration: 2 minutes and 28 seconds
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Language: English
License: Dotsub - Standard License
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Views: 19
Posted by: pgtranscribes on Apr 10, 2015

3.Why do we have seasons

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