ATS 210 Spring Term 2001 NAME: Final Examination This is a 2 hour, closed-book examination. Calculators may be used. All answers should be written on the examination paper. Use the final sheet for any notes or rough workings. Your answers must be your own work. NOTE: Academic dishonesty is a serious offence that may result in grade penalties and other disciplinary action. SIGN HERE: I have read the statement about dishonesty and understand the consequences.. Part A Answer ONLY TWELVE QUESTIONS in Part A. (Each question is 3 points) 1. (Circle the correct answer) The boundary between the troposphere and the stratosphere is called the tropopause / stratopause/ mesopause 2. (Circle the correct answer) Near the surface of the earth, the atmospheric pressure decreases by about 1, 10, 30, or 100 mb for every 100m increase in elevation. 3. Changes of state involving phases of water are important for the latent heat energy associated with them. Name three processes involving changes of state that require energy to be supplied from the environment (i.e. that result in cooling of the environment) 4. (Circle the correct answers) Solar radiation energy reaching the earth s surface is mainly in the waveband 0.3-3 micrometers, 30-300 micrometers, or 0.3-3millimeters ; longwave radiation emitted from the earth s surface is mainly in the waveband 0.3-3 micrometers, 3-30 micrometers, or 30-300micrometers. 5. List three greenhouse gases that have increased in concentration over the last 50 years in the global atmosphere. 6. List the three resistances that control the rate of heat loss from the core of an animal to the surrounding atmosphere. Which of the resistances are directly influenced by wind speed? 7. On a cold, windy day, a weather station reported that the air temperature was -8 C and the Wind-chill Equivalent Temperature was -25 C. Explain what is meant by Wind Chill Equivalent Temperature. 1
8. (Complete the definition) Relative humidity is.. 9. (Complete the statement.) The dry adiabatic lapse rate is greater than the moist adiabatic lapse rate because. 10. Circle one of the following mechanisms that is not a primary way by which clouds form. (a) lifting over topographic barriers (b) forced lifting along weather fronts (c) surface heating and convection (d) lifting by supersaturation (e) lifting by convergence 11. The figure below shows an upper air (500mb) map. (a) Explain the meaning of the solid contour lines (b) Explain the meaning of the arrows (c) Outline the zones of flow divergence on the map 12. Briefly explain how radiation fog is formed. 2
13. The satellite image below is of the Yucatan Peninsula in Mexico. Briefly explain the processes that probably produced the observed cloud pattern along the north coast (top) of the peninsula. 14. Name the 2 processes that cause cloud droplets to grow large enough to precipitate 15. Draw a side view of a typical warm front. Include details of (a) the common cloud types you would observe, (b) the horizontal scale of distance, and (c) the locations of warm and cold air at the surface. 16. List four atmospheric conditions necessary for creating a high probability for a major air pollution incident. 3
Part B NAME: Answer ONLY THREE QUESTIONS in Part B. (Each question is 5 points) 17. The sketch below shows evenly spaced isobars indicating a constant pressure gradient from south to north at an altitude above the friction level. Sketch a rough path along which an air parcel starting at point A would accelerate until it reached a steady speed, and indicate the magnitude and direction of the forces acting on it at several points on its path. North 900mb 904mb 906mb A South 18. Describe three ways by which a fruit farmer might protect his trees from damage on cold nights in spring. 19. Explain, with the aid of a diagram, what happens to a rising parcel of air when the atmosphere is conditionally unstable. In your example, choose values of the air temperature and dew point temperature at the ground and assume an appropriate value for the environmental lapse rate. (HINT: the dry adiabatic lapse rate is 10 o C per km, and the moist adiabatic lapse rate is typically about 6.5 o C per km near the surface) 4
20. Explain, with the aid of an example, why the surface air on the downwind side of a mountain can be drier than the surface air on the upwind side. (HINT: values for dry and moist adiabatic lapse rates are given in Question 19) 21. Briefly explain what causes the upwelling of cold water along the Oregon coast in summer. 22. If you were given a surface weather map showing isobars, weather fronts and current observations, and a 500mb upper air chart, how might you use this information to predict where a storm would move and how it would develop over the next 24 hours? 5
Part C Answer ONLY ONE QUESTION from Part C. (Each question is 9 points) 23. The net radiation measured over a dense forest in Oregon at noon on a cloudless June day was 730 W m -2. Given the following other measurements made over the forest, calculate the temperature of the top of the forest canopy, assuming that the foliage radiated like a perfect black body. Downward solar radiation 900 W m -2 Albedo 0.10 (10%) Downward longwave radiation 400 W m -2 (HINT: Stefan s Law L= σt 4 where σ is 56.7x10-9 W m -2 K -4, and T is the temperature in degrees Kelvin.) 24. A student using a wet-and-dry bulb thermometer for his project breaks the dry bulb. He measures a wet bulb temperature of 10.0 o C. A friend tells him that the vapor pressure in the atmosphere is 10.0mb. (a) What dry bulb temperature would he have recorded if the thermometer had not been broken? (b) What is the dew point temperature of the air? (c) What is the relative humidity? [HINT: the wet bulb equation is e = e s(tw) - γ(t a T w ) where e = atmospheric water vapor pressure, e s(tw) is saturation vapor pressure at wet bulb temperature T w, T a is dry bulb (air) temperature, and γ is the psychrometer constant 0.66 mb o C -1. Tables of saturation vapor pressure e s are provided. ] 6
25. At the summit of Mary s Peak (elevation 1250m), a student measures that the atmospheric pressure is 850mb and the air density is 1.07 kg m -3. She then drives to Waldport, on the coast. Using the pressure reading from Mary s Peak, estimate (i) the temperature at the top of Mary s Peak in C (ii) the atmospheric pressure she would measure at sea level in Waldport. [HINTS: (a) Assume that the change of pressure with height is given by P=P o (exp z/h), where P is the pressure (mb) at height z (in km), P o is sea level pressure, and H is approximately 7.6 km. (b) The Gas Law is P= ρ R T where P is air pressure (N m -2 ), ρ is density (kg m -3 ), R is the gas constant of air (287 N m kg -1 K -1 ), and T is temperature (K) (c) 1mb = 100 N m -2, 273 K = 0 C] 26. A student, dressed only in shorts, is partying on a beach in Mexico one night during Spring Break. The air temperature T a is 30 o C, and windspeed u is 5 m s -1. If his rate of heat loss by convection C is 100 W m -2, estimate his skin temperature T s. Explain any assumptions you have made. [HINT: Ignore effects of clothing. Convective heat loss is given by C = a (T s T a ) / r b, where the constant a is 1.2 x 10 3 J m -3 o C -1. Boundary layer resistance r b is given by r b = 307 (d/u) 0.5, where r b is in s m -1 when d is in m and u is in m s -1. Assume that d is 0.17m for the student.] 7