hw2_s09 - Moon line, as shown: Ignore atmospheric effects....

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ABE 4034 Homework Problem Set– 2 Due Date – 1/22/09 Note: If it appears that necessary information is missing from a problem, make a reasonable assumption and state the assumption. 1. Moon reflects about 10% of the incident solar radiation. The Moon is a Lambertian surface (perfectly rough surface). A Lambertian Moon would appear uniformly bright across its disk, i.e., its brightness will be uniform in all directions. Assume no losses in the Sun-Moon-Earth paths Given a solar constant (power density of Sun) of S s = 1370 W/m 2 at the Moon, and Earth- Moon distance of r = 3.8 x 10 8 m. Assume that the Moon subtends an angle of 0.5 ! at the Earth, and the Sun-Moon-Earth geometry and the Moon is a flat disk normal to the Sun-
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Unformatted text preview: Moon line, as shown: Ignore atmospheric effects. a) What is the total solar power reflected by the lunar disk (i.e., P o in Watts)? b) What is the Moons brightness for " = 30 ! (in W m-2 sr-1 )? 2. Sunlight is incident on a Lambertian surface at an angle of 45 to the normal. Assuming that the Sun has an exitance of 6.42x10 7 W/m 2 , a radius of 6.96x10 8 m and is at a distance of 1.5x10 11 m from the Lambertian surface, calculate the brightness of the surface observed by a sensor at 0.4 ! m. Ignore atmospheric effects. 3. Why is the sky blue? Why is it orange/red during sunrise and sunset? r Sun Moon (Lambertian Surface) Earth...
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