--> DUE in class on Wednesday, January 25 at 10:30 am You may handwrite your answers, but please write neatly and large enough so we can read it. 1. Pluto's atmospheric composition is similiar to Earth's. It is predominantly nitrogen, with a little carbon monoxide and methane. At its closest approach, Pluto is 30 times further from the sun than Earth, and its surface temperature is cold enough to condense nitrogen gas into nitrogen ice. Pluto's orbit is peculiar. Its spin axis lies nearly in its orbital plane around the sun, so at solstice one hemisphere receive nearly all of the sunlight and the other is virtually all dark (See our textbook Fig 4-15, but tilt the axis 90 deg, instead of 23.5 deg). Naturally the lit hemisphere is warmer than the dark hemisphere, so nitrogen ice tends to sublimate slowly from the warm hemisphere and condense in the cold one. a) Estimate the surface temperature on Pluto's lit and dark sides using planetary energy balance, but include sublimation and evaporation as follows: Lit side (receives all of the incoming sunlight, surface is sublimating): S*(1-A)/2 = sigma * Tlit4 + Fsub Dark side (receives no incoming sunlight: surface is condensing): Fsub = sigma * Tdark4 All fluxes are averaged over one hemisphere. There is a factor of 2 (rather than a 4) in the first equation, because the sunlight is only distributed over one-half of the sphere for long periods of time. Let Fsub = .2 W/m2 be the energy flux leaving the surface on the lit side and received by the surface on the dark side due to sublimation and condensation, respectively. Let the albedo A = 0.45 and the solar constant for pluto S = 1.5 W/m2 (We guessed values for Fsub and A and estmated S from the inverse square law S= So(ro/r)2 = 1370 (1/30)2 , also note that sigma = 5.67 X 10 -8 W/m2/K4 for all planets. We can ignore the greenhouse effect because the concentration of greenhouse gases is very low.). b) In about 30 words summarize your results, regarding temperature and the heat transport via sublimation and condensation. Check out a recent newspaper article about pluto sublimation for fun/more information 2. Sketch a map of Africa (hand drawn is fine) and referring to Fig 4-26 discusss which areas you think have high and low rainfall (include the time of year) as a result of the position of the ITCZ, monsoons, prevailing winds and location of mountains. Explain your reasoning. 3. Refer to Fig 4-17 in your textbook and your knowledge about what causes cloud formation to describe where you are most likely to see clouds develop in the figure panels. 4. In your own words: Explain why Earth experiences different seasons throughout the year. Which parts of Earth experience the greatest seasonal range in temperature (see Fig 4-18c), and which parts experience the least? 5. Imagine that a low pressure system is due south of Seattle, and a high pressure system due north. Assuming straight isobars and perfect geostrophic balance, which way is the wind blowing in Seattle? Include a force-balance diagram like in Fig 4-13. 6. In your own words describe water vapor feedback: (a) what is it? (b) Why is it a positive feedback? (c) Why isn't there a runnaway greenhouse effect on Earth? |