UNIVERSITY OF EAST ANGLIA School of Environmental Sciences Main Series UG Examination METEOROLOGY I ENV-5008A. Time allowed: 2 hours

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1 UNIVERSITY OF EAST ANGLIA School of Environmental Sciences Main Series UG Examination METEOROLOGY I ENV-5008A Time allowed: 2 hours Answer ALL questions in Section A in the space provided on the exam paper. If the space is insufficient, please use a separate answer book. ALL Section A questions carry equal marks, together they represent 50% of the exam marks. Answer TWO questions from Section B, each in a SEPARATE answer book. All Section B questions carry equal marks, together they represent 50% of the exam marks. Figure 1 is attached as separate sheet Notes are not permitted in this examination. Scientific calculators are allowed. Do not turn over until you are told to do so by the Invigilator ENV-5008A Module Contact: Roland von Glasow, ENV Copyright of the University of East Anglia Version 2

2 2 SECTION A (one hour): Answer ALL questions. Each question carries equal weight. (1) (a) Which state variable of the atmosphere is measured by an aneroid barometer? Give the units. [20%] (b) Describe how an aneroid barometer works. [40%] (c) How can a single barometer be used to forecast the weather? [40%] (2) The atmosphere of Mars is composed primarily of 3 gases, as shown below: Gas Specific mass Molar mass Mi (g mol -1 ) Carbon Dioxide Nitrogen Argon K mi M = 1/ = (a) Calculate the mean molar mass of the atmosphere of Mars using i 1 mmi where mi/m is the specific mass (mass concentration) and Mi is the molecular mass. [20%] (b) Calculate the dry specific gas constant (R) for Mars, given the universal gas constant R*=8.314 J mol -1 K -1 [20%] (c) Write down the ideal gas law. For Mars, calculate the density of an air parcel with pressure 6 hpa and temperature -30 o C (i.e. typical surface values). [30%] (d) How does the composition of Mars atmosphere differ from Earth s atmosphere? [30%]

3 3 (3) Sketch the sequence of cloud types in an idealised example of the passage of a frontal system (as would be shown in a text book) where a warm front is followed by a cold front. Briefly explain why the sequence is occurring the way you sketched it. (4) Why do low clouds emit more infrared radiation than high clouds of comparable optical thickness? Name the underlying physical law and give the relevant formula. TURN OVER

4 4 (5) a) Explain the meaning of the terms geostrophic, gradient and cyclostrophic winds. Include diagrams and/or equations in your answer. [80%] (b) Describe, therefore, the possible causes of ageostrophic flow. [20%] END OF SECTION A

5 5 SECTION B (one hour): Answer TWO questions from this section. 6 (a) The first law of thermodynamics for an air parcel can be written as: dq = cpdt (RT/p)dp, where R is the specific gas constant, T is temperature and p is pressure. Explain what dq, dt and dp represent. Define the constant cp and explain what it is. Given R= 287 J kg -1 K -1 for dry air, calculate cp for dry air. What assumptions have you made? [30%] (b) An air parcel at the foot of the Grampian Mountains has an initial temperature of 30 o C and initial pressure of 900 hpa. The air parcel ascends isothermally up to the top of the mountain at 700 hpa. What is the temperature at the mountain top? What change in heat does the air parcel undergo? [20%] (c) On the side of the mountains there is a pool of cold dense air up to the height of the mountain top. A separate air parcel is advected downwind, at a wind speed of 20 m s -1, on top of this cold-air pool and thus cools isobarically. Calculate the temperature of the air parcel at a distance of 5 km downwind, assuming the air parcel loses heat at a rate of 10 W m -2. State any additional assumptions made to estimate the air parcel s temperature. [30%] (d) An isothermal ascent up the mountain is not particularly realistic as one might expect an adiabatic cooling during ascent. Describe what adiabatic cooling means. If the air approaching the mountains is relatively humid then the cooling during ascent may be lower, explain why this would be the case? [20%] (7) (a) In meteorology the terms longwave radiation and shortwave radiation are often used. Explain what is behind this distinction. For each of the above, give the approximate wavelength range and state the origins of this radiation. [20%] (b) State and explain Wien s law. What other radiation law does it follow from? Calculate the Sun s emission temperature if the wavelength of maximum emission is λmax=0.5µm. [20%] (c) Show, using a sketch, that the amount of energy received by the Earth from the Sun is determined by an inverse square law. Assume that the solar constant for the Earth is S0=1368 W m -2. What is the solar constant for Mars if the distance from sun is 1.52x the Sun-Earth distance? [20%] (d) What does the term atmospheric window refer to, and what wave length range does it cover? [20%] (e) Briefly explain the natural greenhouse effect and name the main gases responsible for this effect. [20%] TURN OVER

6 6 (8) The plotted chart (attached, Figure 1) shows surface observations for the 2nd February 2009 at 02:00. a) Construct isobars at 4mb intervals on the plotted chart. [50%] b) Describe the variation of weather conditions across the chart, paying particular attention to the distribution of temperature, dew-point temperature, wind speed, wind direction and present weather reports. [50%] END OF PAPER

7 7 Figure 1: Surface Plotted Chart for 00:00UTC on 2 nd February Registration No....