Sample Exam Questions

Sample Lab Exam 1 Questions

WARNING: The lab exam example questions for both lab exams are actual exam questions from a course which had 120 minute lab exams (not 50 minutes), and some labs which were different from those in ENVS 201. Please bear this in mind when using these examples in preparation for ENVS 201 lab exams.

[NOTE: You may need to refer to the data below to answer some questions]

Distance from Earth to moon: 3.84 x 10⁸ m; Radius of Earth: 6.37 x 10⁶ m
Radius of Sun: 7 x 10⁸ m; Distance between Earth and Sun: 1.5 x 10¹¹ m
Surface area of a sphere: 4$\pi$R² ; Surface area of a circle: $\pi$R²
Solar constant: 1353 W m^-2 ; L_V = 2.5 x 10⁶Jkg^-1
Stephan-Boltzmann Law: E = $\epsilon$$\sigma$T⁴ ; $\sigma$ = 5.67 x 10^-8 W m^-2 K^-4
Wien's Law: $\lambda_{{\mbox{max}}}^{}$ = ${\frac{{2.88 \times 10^{-3}}}{{T_{0}}}}$ (m); Kirchoff's Law: a_$\lambda$ = $\epsilon_{{\lambda}}^{}$
Cosine Law of Illumination: K_EX = I₀cosZ ; cosZ = sin$\phi$sin$\delta$ + cos$\phi$cos$\delta$cosh
$\delta$ = - 23.4 cos(360(T_J+10)/365) ; Kelvin = ^o Celsius + 273.17
Radiation budgets:

K^* = K $$\downarrow$$ - K $$\uparrow$$ = K $$\downarrow$$ (1 - $$\alpha$$)

L^* = L $$\downarrow$$ - L $$\uparrow$$

L^* = L $$\downarrow$$ - $$\sigma$$T₀⁴

L^* = L $$\downarrow$$ -  ($$\epsilon$$$$\sigma$$(T₀)⁴ + (1 - $$\epsilon$$)L $$\downarrow$$ )

Q^* = K^* + L^*

$$\downarrow \uparrow \downarrow \uparrow$$ =

Energy balances:

Q^* = Q_H + Q_E + Q_G

Q_E = L_VE

1. Given that the radiation temperature of the earth-atmosphere is about 254 K, assuming it is a black body, calculate the flux density of longwave radiation (W m^-2 ) emitted by the earth-atmosphere. What is the total flux emitted (W) by Earth? (10 points)

2. The flux density of Earth radiation reaching the moon can be viewed as that on a spherical shell concentric about Earth whose radius is the mean distance between Earth and the moon. Calculate the value of this flux density. How does this compare with the solar constant? (10 points)

3. The sun is 20 ^o above the horizon. Calculate K_EX the flux density of radiation entering the atmosphere. If the atmosphere absorbs or reflects 20 % of this value, and the earth's albedo is .25, what is K^* , the net short wave radiation? (10 points)

4. Consider a very dry soil and scrub landscape at midday where
   K $$\downarrow$$ = 800Wm^-2, L $$\downarrow$$ = 300Wm^-2,$$\alpha$$ = 0.25, T_o = 36^oC.

   Overnight a severe thunderstorm soaks the area. At midday on the following day the incoming radiation terms are identical with the day previous but $\alpha$ = 0.17 and T_o = 24^oC . Calculate the change in the value of Q^* between the two occasions (you may assume the surface acts as a blackbody for longwave radiation). If the surface emissivity also dropped, would that augment or diminish the change in Q^* ? Explain your reasoning. (10 points)

5. Earth-Atmosphere Radiation Budget

   Using your understanding of the concept of radiation balance complete the missing values in the following table of the annual radiation balance of the Earth (E), the Atmosphere (A) and the Earth-Atmosphere system (E-A). All units are in GJ m^-2 year^-1 (G = 10⁹ ). You are given the average annual solar radiation to the E-A system ( $\overline{{K_{EX}}}$ ) is 338 W m^-2 (see Lab 2), the planetary albedo ( $\alpha_{{E-A}}^{}$ ) is 0.30 and the two values inserted in the matrix. ^D.1 (10 points)

   	Net solar	Net infra-red	Net all-wave
   System	(K* )	(L* )	(Q* )
   A			-3.02
   E	5.14
   E-A

Sample Lab Exam 2 Questions

[NOTE: You may need to refer to the data below to answer some questions]

$$\rho \mbox{ J kg$^{-1}$ K$^{-1}$}$$

$${\frac{{\Delta p}}{{\Delta z}}} \rho$$

$${\frac{{1}}{{\rho f}}} {\frac{{\Delta p}}{{\Delta n}}} {\frac{{g}}{{f}}} {\frac{{\Delta Z_p}}{{\Delta n}}}$$

$${\frac{{V^2}}{{R}}} {\frac{{1}}{{\rho}}} {\frac{{\Delta p}}{{\Delta n}}}$$

$${\frac{{V^2}}{{R}}} {\frac{{1}}{{\rho}}} {\frac{{\Delta p}}{{\Delta n}}}$$

$${\frac{{g}}{{f}}} {\frac{{\Delta(Z_{P2} -Z_{P1})}}{{\Delta n}}} {\frac{{R_d}}{{f}}} {\frac{{\Delta p}}{{p}}} {\frac{{\Delta T}}{{\Delta n}}}$$ Q_E = L_vE

$$\mbox{ kJ kg$^{-1}$ at 20 \mbox{$^{\circ}$}C}$$

$$\Delta \Delta$$

$${\frac{{e}}{{e^{*}_{(T)}}}} {\frac{{r}}{{r_s}}}$$ vpd = (e^*_(T) - e)

$$\lambda \lambda \mbox{Pa \mbox{$^{\circ}$}$\mbox{C}^{-1}$}$$

$$\Omega \phi \Omega$$

$$\mbox{m $\mbox{s}^{-2}$}$$

1. Give the principles behind using a psychrometer to measure atmospheric humidity. If the wet bulb temperature is 10 ^o C, and the air temperature is 15 ^o C, calculate the vapour pressure and relative humidity. (5 marks)
2. A cool winter Canadian air mass with a temperature of -4 ^o C and a relative humidity of 91% meets a warm air mass sweeping northward from Texas with a temperature of 17 ^o C and a relative humidity of 26%. In the mixing process will the southern border of the Canadian air gain or lose water vapour content? Explain. (5 marks)
3. To answer this question, make reference to figure D.1.
   1. Explain the rather ``anomalous'' dip in the Q_E curve (and the related rise in Q_H ) in July and August. (5 marks)
   2. How is it possible for the heat used in evapotranspiration (Q_E ) to exceed the available net radiation (Q^* ) in the September-February period? (5 marks)

   Figure D.1: Monthly averaged annual energy budget for Vancouver.

   
4. 1. Plot the data from table D.1 on the tephigram at the end of this exam. There will be two vertical profiles, one of T at each pressure level, and one of T_d at each pressure level. (2 marks)

   2. Complete the table using Normand's rule to find T_w and also find the relative humidity (RH). (3 marks)
      

      Table D.1: Vertical sounding data

      Pressure	Temp.	Dew pt. T	Wet bulb T	mix. rat.	rel. hum.
      P (hPa)	T (o C)	Td (o C)	Tw (o C	r (g/kg)	RH (%)
      1000	29	11
      850	15	11
      700	4	1
      650	8	2
      500	-11	-19
      400	-25	-30

      
      
   3. On the vertical profile you have plotted, find the lifting condensation level (LCL) for a parcel lifted from the surface. Continue to lift the (now saturated) parcel to where it crosses the environment again. What is this level (in hPa)? What is it called? (2 marks)
   4. Identify the stability of each layer on your plotted vertical profile. (3 marks)
5. Calculate the geostrophic wind speed and indicate its direction for the scenario shown below. (3 marks). What are the assumptions upon which the geostrophic wind is based? (3 marks).