Lab 10 - April 20, 2007 ARSC 011 Lab No. 10 Lab No. 10...

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April 20, 2007 ARSC 011 Lab No. 10 Lab No. 10 Earth’s Seasons and Lunar Cycles 1. A Reason for the Seasons When it’s summer here in Milwaukee, WI, it’s actually winter in Buenos Aries, Argentina, and vice versa in the winter. This is because seasons are based on temperature changes, not the calendar year. For example, the warmest part of the year is known as summer, whether it’s July or December, depending on which hemisphere one is in. In order to explain why we experience four different seasons in Milwaukee, an explanation of these temperature changes must be given; for only then can we discover the reason for the seasons here in Milwaukee. Figure 1.1 shows an “outer space” view of the Earth’s orbit and tilt around the sun during each season’s peak month. For example, the “summer solstice” shows Earth’s tilt and orbit during July/January and the “winter solstice,” January/July. Daily temperatures, which regulate particular seasons, vary depending on the amount of sun that remains above the horizon for a certain amount of time. Then we must ask, what regulates how long the sun is above the horizon? And what regulates the amount of sun in the sky? The answer to both questions is the same: the tilt of the Earth. The tilt of the Earth remains a constant 23.5 degrees. Because of the Earth’s orbit around the sun and its own 1 revolution/24 hrs., combined with its relatively permanent tilt, different parts of Earth are tilted towards and away from the sun during different times of the year. In Figure 1.1, Milwaukee [and the rest of the Northern Hemisphere, are tilted towards the sun. Thus, the sun is directly above Milwaukee for the longest period of time and its rays are strongest and most direct during this time. Therefore, when a particular hemisphere is
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tilted towards Earth, it will experience summer. Also, when one hemisphere is pointed towards the Earth, the other is not. This explains why places like Buenos Aries in the Southern Hemisphere experience winter during our Milwaukee summers. Figure 1.2 is an excellent illustration of the northern hemisphere’s seasons according to temperature. You can see that the northern hemisphere is hottest in the summer and coolest in the winter – and that the southern hemisphere is just the opposite. As far as autumn and spring are concerned, think of it as Earth’s “transitioning period.”
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This lab report was uploaded on 04/18/2008 for the course ARSC 10 taught by Professor Buxton during the Fall '08 term at Marquette.

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Lab 10 - April 20, 2007 ARSC 011 Lab No. 10 Lab No. 10...

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