G109 Alternate Midterm Exam October, 2004 Instructor: Dr C.M. Brown

Transcription

1 1 Time allowed 50 mins. Answer ALL questions Total possible points;50 Number of pages:8 Part A: Multiple Choice (1 point each) [total 24] Answer all Questions by marking the corresponding number on the NCS form and on this paper Use only the pencil provided to mark answers on the NCS form Only one answer per question. Multiple answers will be treated as incorrect 1. Which of the following is a conservative measure of humidity a. absolute humidity b. relative humidity c. specific humidity d. none of these 2. Vapor density is a. a measure of humidity on the atmosphere b. an expression of pressure exerted by water vapor molecules in the atmosphere c. does not change with temperature d. none of the above 3. The annual surface radiation budget a. is balanced at the equator b. has a deficit at the equator c. has a surplus in the tropics d. is balanced at all locations across the earth e. is balanced only over the oceans 4. During the summer air temperature usually peaks in mid- late afternoon because a. the Earth is closest to the sun then. b. the solar altitude is highest then. c. solar radiation peaks at noon and input continues during the afternoon. d. the land/water distribution has the strongest effect then. 5. Why do latitudes greater than 66.5 o N and 66.5 o S. experience a 24 hour period of darkness because a. they are much further away from the sun b. they are the furthest extent of the subsolar point c. of the tilt of the earth on the ecliptic and the direction of the axis which always points to Polaris d. of the tilt of the earth on the ecliptic and changes in the absolute direction of the axis 6. The coldest part of the atmosphere is the a. Thermosphere b. Stratopause c. Troposphere d. Mesopause

2 2 e. Mesosphere 7. What percent of earths radiation occur in the far infrared range of the radiation spectrum a. 37% b. 50% c. 43% d. 100% 8. Wien s Displacement Law states that a. a rise in temperature only increases the total radiation b. maximum emittance is in the longer wavelengths c. the hotter the body the shorter the wavelength of maximum emittance d. the hotter the body the longer the wavelength of maximum emittance 9. Global radiation can be balanced a. only at the surface b. only in the atmosphere c. only at the top of the atmosphere d. at the surface, in the atmosphere and at the top of the atmosphere 10. The oceans heat up much slower than the land because a. there is more water than land b. water has a higher specific heat than land c. land has mountains that reach higher up into the air d. a,b e. a,b,c 11. Great Britain and Western Europe is much warmer than one would expect at those latitudes because of a. the North Equatorial Current b. the North Atlantic Drift and prevailing Westerllies c. the North Pacific Current and prevailing winds d. The greenhouse effect 12. Our day-night cycle is a result of a. distance of earth from the sun b. the revolution of the earth around the sun c. the Aphelion and Perihelion d. the rotation of the earth on it axis e. only a and b 13. If there is an increases in air temperature (all else been constant) a. saturation vapor pressure goes down and RH goes up b. saturation vapor pressure goes up and RH goes up c. saturation vapor pressure goes up and RH goes down

3 3 d. saturation vapor pressure goes down and RH goes down e. none of the above 14. Which of the following surfaces is most likely to have the lowest Bowen ratio? a. concrete pavement b. hay field c. desert d. freshly irrigated cotton field 15. Which of the following is not a permanent gas a. oxygen b. argon c. nitrogen d. carbon dioxide 16. Another name for the troposphere is a. the ozone layer b. the laying flat layer c. the weather layer d. the thermal layer 17. Volcanic eruptions can a. increase incoming shortwave radiation b. increase earth s albedo and decrease global mean temperature c. lower earth s albedo d. increase global mean temperature 18. This method of energy transfer does not require a transport medium. a. conduction b. convection c. radiation d. all of the above 19. Convection a. does not involve an actual transfer of energy b. involves potential energy only c. occurs only in liquids and gasses d. is another term for conduction 20. In what month of the year are sun angles in Bloomington (40 o N) lowest a. June b. December c. March d. September e. None of these

4 4 21. How is energy transferred from the sun to earth a. radiation b. sensible heat c. convection d. latent heat 22. In what part of the spectrum does the sun have its peak energy emission: a. visible b. near Infrared c. ultra-violet d. far infrared 23. Reflectivity of the surface is expressed as a. emissivity b. ability to absorb c. albedo d. transmission 24. Radiation absorbed at the earth s surface a. is converted to heat b. causes the enhanced greenhouse effect c. is not connected to sensible and latent heat d. allows us to see colors

5 5 Part B: Short Answers, Fill in the Blanks and Numerical. [total points 26] Answer in space provided. Show all calculations and methods. Don t forget to check and show units Write very clear and legibly. Attempt all questions Equations and constants are given on the last page 1. List the importance of the atmospheric windows for earth s climate (1) 2. List the reasons for variations in Earth s climate, seasons, and day length (2) 3. What is the solar altitude at noon in Bloomington on June 21.(2) Answer

6 6 4. You are at the base of Mt. Everest (thinking of climbing). The air temperature is 15 o C, the air pressure is 78 kpa, vapor pressure is 0.2 kpa and the saturation vapor pressure is ~1.7 kpa. You have a celebration balloon with a volume 0.25 m 3 of dry air, and a temperature equal to that of the air.. a) What is the density of the atmosphere at the base of the mountain? (2) Answer: b) What is the percent of unsaturation of the air (1) Answer: c) You climb the mountain up to 6000 m. above sea level. What changes would be expected in the atmosphere. (2) d) What happened to the balloon you are carrying (hint: what is the fraction of air pressure at this height to that at sea level. use this information and the supplied equation to confirm your answer if you wish but not necessary) (1)

7 7 e) Calculate the amount of energy emitted by the balloon at the base of mountain, assuming an emissivity of (2) Answer: f) Calculate the peak wavelength of energy emission of the balloon at the base of the mountain. (1) Answer Answer 5. Fill In The Blanks (one point each) [total points 12] a) The troposphere extends up to ~ km. b) The earth s source of energy is c) The name of the three ranges on the electromagnetic spectrum important for weather and climate are : 1), 2) 3), and their corresponding observable effects are 1), 2), 3) d) Blue sky is a result of scattering and white/grey clouds a result of scattering. e) Weather is to as an is to population

8 8 Wien s Law Stefan- Bolztmann Law Radiation λ max = a T F tot = σ T Balance K * = K ( α ) Ideal Gas Law Q P * = = ρ λ max wavelength of maximum emission (µm) T emission temperature (K) a= 2897 µmk 4 ε F tot total irradiance (W m -2 ) K K + L L * 1 L R T = Boyle s Law P1 V1 = P2 V2 m R T V Conversions K = C Pa = 10-3 kpa = 10-2 mb T emission temperature (K) ε emissivity σ= W m -2 K -4 Q * net radiation (W m -2 ) K, shortwave radiation in, reflected L, longwave radiation out, in (W m -2 ) α albedo P pressure (Pa = J m -3 ) ρ density (kg m -3 ) = m V m mass (kg) V volume (m 3 ) R gas constant (air) = 287 J kg -1 K -1 T temperature (K) Temperature: Celsius to Kelvin Pressure: Millibar to Pascal Note: a dot means you multiply Hand in all pages