Homework2_key - Written Assignment 2 Solutions NATS 101,...

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Written Assignment 2 Solutions NATS 101, Sec. 13. Fall 2010 1. The principal factor causing the occurrence of seasons is the Earth±s obliquity, or the tilt of the Earth with respect to its orbital plane. The obliquity causes the zenith angle of the sun and the length of day to change (except at the equator) over the course of a year, affecting the net amount of solar radiation received at Earth±s surface. 2. Barrow, Alaska, located north of the Arctic Circle is at much higher latitude than Tucson, Arizona. Hence, the zenith angle of the sun in Barrow is much larger than for Tucson (i.e. the sun is very near the horizon all day in Barrow and much higher in the sky in Tucson), even though the day is 24 hours in length. As a result of the increase in the zenith angle of the sun in Barrow, the sun±s radiation is much weaker because sunlight has to travel a longer distance through the atmosphere during the course of which it gets more diffuse and more attenuated by gases. 3. In the western U.S., small temperature changes can cause major changes in soil moisture. Because the sun is always located to the south at solar noon in the northern hemisphere, hills that face south receive much more sunshine causing greater rates of evaporation resulting in slightly drier soil conditions. So, the northward facing, shadowed side of a mountain has dense areas of vegetation, while the sunlight south facing side has relatively sparse vegetation. This will hold true for all mountains in the Northern hemisphere. The reverse would be true in the southern hemisphere, as the sun would always be located
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Homework2_key - Written Assignment 2 Solutions NATS 101,...

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