Introduction
EXAM
Meteorology and Climate
MAQ-21806
Read this first •
1.
Clearly list your NAME, REGISTRATION NUMBER, YEAR OF ARRIVAL and
STUDY PROGRAM on the left top corner of EACH (so also on the appendices) paper
you hand in.
2.
The unlined A4-papers are meant for draft work and should not be handed in.
3.
Write clearly and well organized. The aim of the exam is to evaluate whether you
understood the course sufficiently; please let this become obvious from clear answers
to the questions.
Furthermore think about:
Clearly show which steps are necessary to perform the calculations you make!
No points will be offered for unreadable answers.
Also for lack of units, as well as for incorrect use of significant numbers, your
scores can be reduced.
4.
The exam consists of two parts. First make Part 1, (CLOSED book) the mark for this
part will weigh 40%. After handing in Part 1, you can start with Part 2 (OPEN book),
which weighs 60%. Don't spend more than 1 hour on Part 1!
Part 1: 7 Exercises for in total 240 points.
Part 2: 3 Exercises for in total 210 points.
5.
Verify(!!) whether you received (apart from answer sheets and draft papers):
Appendix 1: A thermodynamic diagram.
Appendix 2: An isohyps chart.
6.
After the exam, the question sheets should
be handed in as well.
7.
If you did not fill out the course evaluation
yet, we will appreciate it very much if you
will do so.
8.
Please fill out the additional course
evaluation handed out during the exam.
Success!
Meteorology and Climate
1 of 8
Part 1 • Closed book
Part 1 •
Closed Book
Exercise 1 Temperature
Meteorology covers a number of temperature variables. Give a definition of description or the
following temperature quantities:
10p. 1a. Wet bulb temperature.
10p. 1b. Physiological equivalent temperature (PET).
Exercise 2: Turbulence
10p. 2a.
10p. 2b.
10p. 2c.
Exercise 3 Budget equations
10p. 3a.
10p. 3b.
10p. 3c.
10p. 3d.
10p. 3e.
Explain what is meant by Reynolds decomposition, and why it has been introduced.
In the case we can measure the wind speed (both u, v, and w component) 20 times per
second, it appears that u and w fluctuations are always negatively correlated. Explain
this using a drawing.
Give a definition or description of the Richardson number.
What is the key difference between the Langranian and Eulerian framework.
Give in words the four processes that govern the Eulerian momentum budget in the
lower atmosphere. Copy the equation and your answer to the answer sheet.
∂U
= ... + ... + ... + ... .
∂t
Which forces are neglected when using the geostrophic wind speed concept?
Give 2 different weather systems for which the cyclostrophic wind equation is valid.
Motivate your answer.
Explain why the predictability of weather and climate is fundamentally limited.
Exercise 4 BoundaryBoundary-Layer Meteorology.
In figure 1 the evolution of the boundary layer is sketched.
15p. 4a. Give the names of all the layers, A-G.
15p 4b. Draw for the time at the thick arrow (!!), the vertical profile of potential temperature,
specific humidity and wind speed (i.e. their magnitude). (Height at y-axis).
Figure 1: Boundary layer domains (from: Garratt, 1992).
Meteorology and Climate
2 of 8
Part 1 • Closed book
Exercise 5 Climate
10p. 5a.
10p. 5b.
10p. 5c.
How is the solar radiation at the surface influenced by high and low clouds.
What is the effect of low level clouds on air temperature near the surface at night.
Idem during the day.
Figure 2 shows a systematic picture of the climate system.
10p 5d.
10p. 5e.
10p. 5f.
Explain the meaning of ∆FTA and ∆FTA’.
What is the meaning of the squares H1 - H5? The processes are so-called ..... processes
(give the word on the dots).
List 3 of the 4 other processes than “Water Vapour” that apply to boxes H1, H3 -H5.
Figure 2: A systematic picture of the climate system (figure from Peixoto and Oort, 1992).
Exercise 6 A Chimney
A
B
Figure 3: Two emitting chimneys.
Given the plume from chimneys A and B in Figure 3 above.
20p. 6.
Explain, using your knowledge about turbulence, atmospheric boundary layers and
stratification, which situation is typical for the daytime and which for the nighttime.
Meteorology and Climate
3 of 8
Part 1 • Closed book
Exercise 7: Köhler curve
The Köhler curve describes the competition between 2 processes that govern the growth of
cloud droplets (net condensation/evaporation).
10p. 7a. List the 2 effects.
The figure below shows a certain Köhler-curve and 4 droplets A - D.
20p. 7b. Explain for each droplet whether it will grow to a clouddroplet or not..
B
C
RH environment
D
A
radius
Figure 4: The Köhler curve
End of Closed Book Part.
Meteorology and Climate
4 of 8
Part 2 • Open Book
Part 2 •
5p.
5p.
5p.
5p.
Exercise 8 A Thermodynamic
Thermodynamic Diagram
Given the thermodynamic diagram of 27 July 2008 in De Bilt, Netherlands (Appendix 1).
8a. Was this weather balloon launched at midnight or at noon? Motivate your answer.
8b. Motivate the answers of the following questions based on a construction in the diagram
or a calculation. Determine for the air parcel at 500hPa the:
1. The dew point temperature
2. Relative Humidity
3. Wind direction and wind speed.
Note that:
1 long barb = 10 knots, 1 short barb 5 knots, and 1 triangle 50 knots.
1 knots = 0.5 ms-1
5p.
5p.
10p. 8c.
8d.
5p.
5p.
Open Book
4. Lifting Condensation Level
5. Wet bulb temperature
How many degrees °C should the surface temperature rise before a Cumulonimbus
develops, without addition of energy from other sources? Motivate your answer based
on a construction.
Imagine that the air parcel at the surface receives some additional energy and it ascends
to 400 hPa.
1. What is the name for this additional energy?
2. Determine the parcel’s temperature at 400hPa.
Exercise 9 Wind
20p. 9a.
10p. 9b.
Calculate the wind speed at the 500 hPa level based on the ECMWF-model Forecast
over the Netherlands (●) for Sunday 7 December 2008. (See Appendix 2)
The wind in the boundary layer deviates from the calculated wind speed in 9a. What is
the main cause of this difference? Will the deviation be largest over sea or over land.
On the same Sunday at the Haarweg in Wageningen (12UTC), we measured:
FH = 10 Wm-2 (FH is small since it is winter)
U10 = 3.5 ms-1
10p. 9c.
20p. 9d.
10p. 9e.
Give the typical value for the roughness length for grass.
Calculate the wind speed at 80 m, assuming neutral conditions.
Is the assumption of neutral conditions valid? Please motivate.
Meteorology and Climate
5 of 8
Part 2 • Open Book
Exercise 10 Urban climate
25p. 10a. Due to human activity and the city geometry, the temperature in the city is usually
higher than in the countryside. In this case, the temperature in the city Utrecht is
35.5 °C, the surface temperature in the countryside is 26 °C, the wind speed is 2 ms-1 and
the boundary-layer depth is 2000 m (See also the sketch in Figure 5). These observations
have been inspired on observations of 19 July 2006, during a heat wave.
Suppose a steady-state situation. Also suppose that there insufficient moisture in the air
to provide condensation, that radiative heating ∂R/∂z is 0 Kh-1, and entrainment is
negligible, and that C H = 2 ⋅ 10 −2 . Derive an equation for change of air temperature Tair
with distance x from Utrecht, i.e.
dTair
. Hint: start from the 1-dimensional Eulerian
dx
∂Tair
∂T
∂F
∂R
= −U air − H −
− S Latent
∂t
∂x
∂z
∂z
25p. 10b. Integrate the differential equation to obtain Tair = f ( x ) .
heat budget:
If you did not obtain the result in the previous exercise, then assume for the remainder
of this exercise that the temperature can be approximated for x < 125 000 m as follows:
Tair ( x ) = 35.45 − 9 ⋅ 10 −5 x + 3 ⋅ 10 −10 x 2
10c. The apparent temperature for human beings differs from the measured air temperature,
and is important in decision making of cancellation of sport events in case of
dangerously high temperatures. An empirical formula for heat stress reads as:
AT = T + 0.33 ⋅ e − 0.7 ⋅ U − 4.0 .
Herein AT is the ‘Steadman Apparent’ temperature [°C], e the water vapor pressure
[hPa] and U the wind speed [ms-1]. If AT>32.2ºC sport events will be cancelled.
Calculate AT and evaluate whether the sport event needs to be cancelled,
10p.
1. for the city of Utrecht with a dew point temperature of 9ºC.
10p.
2. at a distance of 40 km downstream of Utrecht.
In the countryside it is usually more humid and we guess the dew point temperature on
the countryside to be 11ºC.
20p. 10d. How far from Utrecht ( x in km) will the sport event not be cancelled?
End of the Exam
TairUtrecht = 35.5 °C
Td airUtrecht = 9 °C
U = 2 m/s
Utrecht
z i = 2000 m
Td countryside = 11 °C
T = 26 °C
Figure 5. The city-countryside system around Utrecht.
Meteorology and Climate
6 of 8
Appendix 1
Name:
Registration number:
Meteorology and Climate
7 of 8
Appendix 2
Name:
Registration number:
564 dam
552 dam
Meteorology and Climate
8 of 8