Environmental physics as a teaching concept

Environmental Physics as a teaching concept by Egbert Boeker, Rienk van Grondelle and Piet Blankert1

Department of Physics and Astronomy, Free University, De Boelelaan 1081, 1081 HV Amsterdam, Netherlands Abstract: Environmental Physics is understood as the physics connected with analysing and mitigating environmental problems. It draws on most sub-disciplines of physics and provides a way of making physics relevant. In this paper the motivation of teaching environmental physics is discussed and examples of course content and supporting student work are given, based on work in the authors’ department. 1. Introduction: defining environmental physics During much of the 19th and 20th century, academic physics was taking the objects of study from the natural environment and performed experiments under controlled conditions. Added to that, data on the natural phenomena were collected and together this resulted in the laws of nature, as physicists describe them. This process is indicated by the dotted lines at position (1) in the lower left corner of Figure 1. In the later part of the 20th century several new sub-disciplines of physics such as biophysics, climate physics or atmospheric physics were born, which operate at the interface of many disciplines. Their emphasis is more on modelling of natural phenomena and testing the models by experiments and data gathering (loop 2 in Fig. 1) than on finding new laws of nature. At the same time the natural, environmental phenomena were heavily influenced by the impact of man. The phrase ‘environmental problems’ was coined. In the textbooks of the first two authors ([1], [2]) the point is made that environmental problems arise from interaction between mankind and nature and therefore they not always are soluble in the sense that a physics problem is soluble. Still, physics may help to analyse, prevent or mitigate environmental problems. The intermediary steps here consist of modelling as input to the political system with decisions alleviating environmental problems as a result (loop 3 in Fig. 1). Here, the physicist cannot choose the particular laws of physics (s)he wants to study; on the contrary, the challenge is to identify which laws of physics are manifest in the problem under scrutiny and what physics knowledge is required to tackle them. Not only that, the other natural sciences such as chemistry and biology, have their own important contribution to make, using their own methodology. A course in environmental physics, as we see it, should point this out and touch on the other natural sciences in examples and exercises.

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Egbert Boeker (1937; [email protected]) just retired from an academic career in which he taught virtually all of the undergraduate courses in physics. Rienk van Grondelle (1949; [email protected]) is doing research in biophysics and teaching not only to physics students but also to biology students and is a member of the Royal Netherlands Academy of Sciences. They added their experiences in writing two textbooks on Environmental Physics ([1] and [2]). Piet Blankert ([email protected]) is a nuclear physicist by origin; since 1987 is he head of the departments’ students lab.

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In this way environmental physics is both similar to and different from the new subdisciplines of physics, such as biophysics. In Figure 1, environmental phenomena then should be replaced by ‘life phenomena’. The similarity is that many laws of nature, experiments and data are required describe life processes. And also that the emphasis has shifted from finding the laws of nature to modelling of the natural phenomena. But the link to politics and decision-making is much weaker. Political decisions may be required to finance a cure for certain cancers, but they will hardly influence the processes within the living cell. In that sense biophysics and most sub-disciplines of physics operate at some distance of the political arena. In contrast, if politicians fail to stop climate change, totally new and unexpected phenomena may occur.

Experiments

Laws of Physics

Environm ental Phenomena

Data

Figure 1. The field of the professional environmental physicist. Where the traditional academic scientist studies a phenomenon under controlled conditions and finds the laws of physics (loop 1), the environmental physicist needs much of the knowledge of physics for modelling the human impact on the environment. Models are tested on experiments and data (loop 2). Finally, political decisions may be made, which alter the manmade environmental phenomena (loop 3). As a typical example of an environmental phenomenon, about which a physicist has to write a report as input to decision making, consider ozone in the troposphere. The physicist should be aware of the following. Biologists have connected tropospheric ozone with plant diseases, which show up as black spot on the leaves. Chemists have studied those proteins, which are very sensitive to O3. Environmentalists have pointed out that humans suffer from eye irritations and coughing and blamed the private car. Fellow physicists have measured the O3 concentrations at different altitudes and economists have calculated the damage to crops and humans and compared these data with the cost of adding catalysts to cars, which will reduce the damage done.

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The last point, that of the economist, illustrates that more than natural science is at stake. One has to put a monetary value to human diseases from (air) pollution, which implies a value judgement on what a healthy human life is worth. Therefore, environmental physics will touch on social and ethical aspects as well. In their recent textbook Mason and Hughes [3] define environmental physics as the response of living organisms to their environment within the framework of environmental processes and issues. The phrase ‘issues’ points to the social and political context of environmental processes. These authors probably aim at political neutrality. This should not suggest that the subject matter of environmental physics is very different whether one uses the approach of Mason and Hughes [3] or of the present authors ([1], [2]). Browsing through the books one will encounter physics concepts, mathematical equations, derivations and formulas. They usually are applied to practical cases and comprise some meteorology, radiation physics and transport phenomena. So, independent of how one defines it, environmental physics is very much physics. It is rather classical and applied, but the fun and joy of understanding natural phenomena, which is the core business of the physics profession, is there. 2. The motivation of teaching environmental physics As written above, environmental problems arise from interaction of man with nature. Environmental physics uses most sub-disciplines of physics to tackle these problems. This leads to various motivations to teach the subject of which we discuss two. The first is improving the students’ understanding of physics. This holds true, both for physics students taking an advanced course, based on ref [1], or for students taking a broader course, based on ref [2]. The second is creating a realistic job perspective for physicists. When one reads the rest of this paper, one may conclude that also the job perspective of general science students, taking course [2] may be improved. improving the student’s understanding Environmental physics comprises many macroscopic phenomena. Therefore it brings physics closer to the students and makes them realize what variables in equations really mean. In the discussion of groundwater for example, one encounters the density of the soil ρ and the density of the groundwater ρw in the combination ρ/ρw. In one of our lectures we asked to guess a realistic value for this ratio. The students did not know and when pressed, one of them mentioned a value of 1000, apparently thinking in units of [kg m-3]. The hydraulic engineers use a ‘thumb’ value of 2 and we would have taken any answer between 1.5 and 5 to be acceptable. After the explanation that units do not occur in ratios these students will never make such a mistake again. Environmental physics draws on many topics some of which also the general science student may have studied already. In that way it connects separate bodies of knowledge and brings them in context. For example, in discussing the greenhouse effect one has to explain how a rising concentration of CO2 or CH4 in the atmosphere increases the temperature at ground level. One needs the absorption spectra of these molecules and the concept of optical density to understand the non-linearity of the effects and the difference between the two compounds.

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It is an important teaching goal to appreciate the non-linearity of many environmental cause-effect relations. Elementary courses usually stress the proportionality of cause and effect, as in Hooke’s law of mechanics. In environmental physics this is different. In absorption of infrared radiation by greenhouse gases for example, two non-linear effects are encountered. The first is that at certain wavelengths CO2 or CH4 already are absorbing 100 % of the radiation. There an increase of concentration will not increase the greenhouse effect. At other wavelengths, the absorption may be small; there, a doubling of concentration will double the optical density OD. According to Beer’s law ([1], p. 21), the intensity of radiation of a certain wavelength along a path with length l decreases exponentially with OD:

I (l ) = I ( 0)×10−OD

(1)

Therefore a doubling of OD will give a strong non-linear increase in absorption. This example also shows that one needs a complex data set like an absorption spectrum to obtain significant results. In traditional physics teaching it is not common to connect the various sub-disciplines. A course in environmental physics offers many opportunities. In groundwater motion for example, in a first approximation the groundwater level φ is a function of the horizontal location (x,y). The volume of water [m3] passing per second per [m2] perpendicular to the flow is q" [m3 s-1 m-2]. This water flow obeys Darcy's equation q" = - k grad φ

(2)

in which k is called the hydraulic conductivity and φ the hydraulic potential. Certainly for physics students, the analogy with Ohm's law q" = - σ grad V is apparent with q" the current density, σ the electric conductivity and V the electric potential. This resemblance also explains the common names conductivity and potential for both cases. the professional perspective for physics students Physics students have several perspectives on the job market: they may start an academic career, go to industry, enter a consulting firm, work for the government or teach at secondary schools. Based on an analysis of US reports Ripin [4] pleads for a ‘full toolbox’ for physics graduates: ‘we should make physics the “liberal arts” of technology by offering greater breadth to graduates. Even those who opt for the traditional, academic path are well served by exposure to the same skills required by those headed for industry: an awareness of rudiments of other disciplines , the ability to write and speak effectively, experience in teamwork, a working knowledge of instruments, an ability to focus on an objective, and an understanding of budgets’ A course in environmental physics with exercises, papers and students labs is one of the ways to achieve this. It does not necessarily take a lot of time. The complete book [1] with exercises and student’s lab would in the Netherlands be rewarded by about 10 % of the total number of credit points of a physics Masters degree. A course of this size would provide an integration of physics insights, frequently combined with concepts from other disciplines, which single topics like quantum mechanics or field theory do not give. 4

3. Increasing scientific literacy Students in other branches of science than physics usually are not interested in single topics within physics. They need a special approach, according to the Physics Survey Overview Committee in the USA [5]. This body, appointed by the National Research Council recommended that “Physics Departments should review and revise their curricula to ensure that they are engaging and effective for a wide range of students and that they make connections to other important areas of science and technology. The principal goals of this revision should be (1) to make physics education do a better job of contributing to the scientific literacy of the general public and the training of the technical workforce and ---“ Environmental physics can serve as a means to achieve this goal. A text like [2] uses mathematics without complicated derivations, and is suitable for university students in a wide range of scientific disciplines. Texts like [2] or [3] and the corresponding courses are not easy, and therefore no ‘soft options’. The reason is that environmental physics connects topics, which usually are taught separately. This implies that there are many concepts and equations to be understood. While for an examination in a subject like mechanics the student may write all relevant equations on the back of a single envelope, this is no longer true for a test in environmental physics. If a student passes the test, (s)he will have a rather broad working knowledge of physics. These courses therefore contribute more to the scientific literacy of natural scientists than a selection of single subjects from the physics curriculum. 4. Examples of course content In this section we discuss two examples of course content. In the first, the difficulty of making accurate predictions of climate change is illustrated, in the second, the relevance of politics is shown. water vapour and climate Climate change and greenhouse gases will form part of any course in environmental physics. It is easy to show the existence of the greenhouse effect, using a radiation balance for the earth with energy in = energy out.

(3)

The ‘energy in’ refers to the solar energy entering the top of the atmosphere. On a plane perpendicular to the radiation, the energy per [m2] is called the solar constant S [W m-2]. The radius of the earth equals R and the backscattering by earth into outer space is a fraction a. So the ‘energy in’ becomes (1-a) S π R2

(4)

The’energy out’ is the infrared radiation emitted by the earth at temperature T , which is approximated by the radiation of a black body. That gives for the right hand side of (3)

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σT4 4 π R2

(5)

with the Stefan-Boltzmann constant σ. Using a =0.30 it follows that the resulting temperature should be T = 255 [K]. The empirical fact that the surface air temperature is more pleasant at an average T = 288 [K], of course is due to the presence of greenhouse gases in the atmosphere. The contribution of these gases to the temperature difference of 33 [K] is given in Table 1, where [ppmv] stands for parts per million in volume. Table 1 Temperature effect of greenhouse gases (see [1], page 33 or [2], page 78) Gas H2O vapour CO2 O3 (troposphere) N2O CH4 Others (CFC;HFC;SF6) total warming effect

Concentration/[ppmv] 5000 345 0.03 0.3 1.7

Warming effect/[K] 20.6 7.2 2.4 0.8 0.6 0.6 33.0

The point, which stands out most prominently in Table 1 is the enormous contribution of water vapour with 20.6 [K]. In a simple exercise the student may calculate that the concentration of water vapour corresponds with 3 [cm] of liquid water. The annual downpour of rain and snow averages about 75 [cm], which means that every 15 days the water content of the atmosphere is replaced. From this simple example it is clear that small changes in water vapour concentration will have large effects and also that such small changes will be difficult to calculate accurately. At this point of the discussion the student already will appreciate the strong nonlinearity in the effects of increasing the concentration of the other greenhouse gases, given in Table 1. During the training the student should learn that in modelling simplifications have to be made resulting in inherent uncertainties in the results of the calculations. The question to the students then is how to present the data of the greenhouse effect and increasing global temperatures (the lower half of Figure 1) to politicians and the general public (the top half of Figure 1). If one stresses the uncertainties and inaccuracies too much, politicians may 'wait and see' before taking unpopular measures. Pointing out uncertainties too little or not at all is against the ingrained basic attitudes and training of our profession. In many professional careers the scientist will have to deal with this question of combining established facts with scientific modelling with the aim of supporting political decision making. Therefore this aspect of our profession has to be prepared in education. At the end of a discussion with students on this point, we usually conclude that the way of presentation will depend on situation and context.

energy use Many environmental problems find their origin in energy conversion and energy use. So, a possible mitigation of environmental problems would be to reduce the energy use, while maintaining the standard of living. It is therefore illuminating to look at the relationship between energy use per person and Gross National Product (GNP) per person in a variety of 6

countries, as shown in Fig. 2. The GNP is taken here as an indication for the standard of living or wealth in a country. An interesting exercise for students is to find out why their own country is so different from similar countries or from their neighbours. For the present paper it is easiest to look at large economies like Japan and the United States. It appears that (in 1998) Japan had a higher wealth for a lower energy consumption. The reasons are diverse: people in Japan use the public transport system much more intensely and the housing area per inhabitant is much smaller. Finally a strong central government is taxing energy heavily, as Japan has no indigenous energy sources. This provides an incentive to industry to put a lot of effort in energy economy. Another aspect of Fig. 2 is that on a global scale the bulk of the people are living in the lower left corner of the graph. They will aim at a higher wealth, so what is their target: the USA or Japan or something else? A connected question is whether all human beings have the same 'right' on the global resources. If so, what energy use should correspond with that right. If that would be the 1998 consumption per person in the USA or even Japan, the question arises whether nature can cope with it. If people do not have equal rights, what would be the ground of that discrimination and is that discrimination sustainable. Will then not the people of the poor countries migrate to the richer ones, legally or illegally? These questions do not have straightforward answers like physics exercises, but they should be discussed, if briefly.

500 Norway Canada

400 USA

Sweden

300

Belgium

Russia Czech

200 Bulgaria

100

Venezuela South Africa Poland

Mexico Egypt

0

United Kingdom

Netherlands Australia France Germany Japan

Switzerland Denmark

Italy

Israel Argentina

Brazil Algeria India

5000

10000

15000

20000

25000

30000

35000

GNP per person/[US$](1990)

Figure 2: Energy consumption per person and Gross National Product per person for a number of countries in 1998. Data were taken from UN statistics (see [2], Fig 11.2)

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. Apart from the aspect of global equity, it is instructive to look at one of the published trend scenarios for the year 2050 [6]. The authors assume a population increase of 50% and the present rate of increase in energy consumption per person. The use of primary energy then increases from 400×1018 [J yr-1] in 1997 to 900×1018[ J yr-1] in 2050. If one would succeed in reducing the use of fossil fuels because of their CO2 emissions from 340×1018 [J yr-1] to 300×1018 [J yr-1] the question is how to find the missing 600×1018 [J yr-1]. At the end of an environmental physics course students should know that renewable energies may be used much more than at present, but they will also know that it has a price. An increase from the present 30×1018 [J yr-1] to for example 300×1018 [J yr-1] will require a considerable effort with financial and fiscal support on a global scale. More than this value seems impossible to achieve. With this argument the authors of ref. [6] argue for expanding the use of nuclear power. Students may object to this conclusion, but then they have to come with a credible counter-argument. The answers to the points raised here cannot be found in a teacher's manual, as values and judgements enter, which go beyond physics. The teacher therefore should participate in the discussion more on equal footing with the students than in matters of physics. The teacher should accept different points of view, but should insist on consistency within the argumentation and consistency with the laws of physics. In this way teaching environmental physics will contribute to the general literacy of the student. 5. Teaching aids As a course in environmental physics is somewhat different in character than standard physics courses, due attention has to be paid to the ways of teaching. Below we consider classroom discussions, computer simulations and the practicals as means to help students to internalise the subject. classroom discussions The example of energy use in the previous section, clearly should be embedded in one or two assignments, which the students prepare at home and then discuss in the classroom. At the end of the course, the student will be aware of the Kyoto Protocol, which is meant to reduce the amount of greenhouse gases in the atmosphere. An assignment could be to assess the realism of the Protocol, to evaluate arguments that the Protocol is based on bad science, that the Protocol does not go far enough, that it favours developing countries, and to take an own position in this discussion. This example is rather on the political side of the spectrum. Most exercises just help the student to internalise the text. As a course comprises a broad range of physics subjects it is essential that students digest the course material immediately after the lecture. In our teaching we stimulated the students to hand in their worked-out exercises two days before the next lecture by giving them credits. At the beginning of each lecture the exercises of the previous lecture were discussed. For the teacher the worked-out exercises will act as an immediate feedback on the quality of his teaching. For the students the general or specific comments of the teacher give them a chance to ruminate and digest the material.

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Classroom discussions will not be restricted to the exercises. Environmental physics refers to subjects, written about in the newspapers. Any teacher by nature will comment on these matters to make the teaching relevant. As the teacher implicitly or explicitly will take a political stand, it is the more important to be open for criticism by the students. If they remain silent, we would suggest to act more and more provocatively until they speak out. computer simulations The simple model of eqs. (3) to (5) gives a temperature for the earth, which is off the mark by 33 [K]. Obviously, one needs better models, where the temperatures of surface and atmosphere are treated separately and where absorption and scattering by surface and atmosphere are taken into account. Such a model is sketched in Fig. 3. Again it is essential that students internalise this model, which gives a zero’th order approximation to the greenhouse effect. It is not sufficient that the model is shown during the course, students should try it at home, and make simple exercises. For example, what would be the effect of a ‘white earth’ with a reflection parameter as º 0.8 instead of the present 0.11. Or, what would be the effect of a cooler sun, as it was a few billion years ago, when the solar constant S was about 1000 [Wm-2] instead of the present Sº1370 [Wm-2]. In order to make the model easily accessible, it is put on the web (www.nat.vu.nl/envphysexp).

Figure 3. Greenhouse model after [1], Fig. 3.2. Left and right show the input parameters and output data of the model. The middle image summarizes in a static way the model used. From [7], Fig. 1 The model of Fig. 3 is easy to program for physics students, although the visualisation is not trivial. A drawback of the model is that no time dependence is included. The fact that the oceans act as a buffer of heat, shifting part of the worldwide climate change to the future is not part of it. In order to get a feeling of this time dependent effect, on the same website the oceans are divided in 10 vertical layers with turbulent diffusion of heat and advection included. In Fig. 4 the result is shown for a block pulse of extra infrared radiation coming down from the atmosphere during 50 years. The student may select other pulses and study their effects and-for fun- when opening the site the negative pulses due to historic volcanic eruptions are shown, which for a short period of time cool down the earth surface. student lab One of the best ways to internalise physics concepts is to work on a student lab. When we started at our institute with the teaching of environmental physics, it was decided to include some special experiments for the group taking the course. As the experiments should

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be real physics experiments – and no ‘soft options’ – it was decided that any physics student could take the environmental experiments as part of his/her lab work. In line with Fig. 1 it was decided to put a problem central and not some law of nature. For example, to test the quality of the photosynthetic process of a forest from an aeroplane in a polluted environment one may use laser remote sensing. That can be prepared in a students’ experiment. Similarly, the hazard of Radon gas in a dwelling depends on the geometry of the building, the ventilation etc. Although the practical is rather conventional, the student has to keep in mind the context in which to apply his or her knowledge.

Figure 4. The oceans-2 model. The top left figure shows an entering infrared block pulse of 50 years of duration. Underneath the temperature effect on the 10 layers is given as a function of time. In the graph on the right the temperature change is given in colour representation. The reader may play with the model on the web by using www.nat.vu.nl/envphysexp. Click’simulations’ and ‘oceans’. From [7], Fig. 4 In order to make the experiments available to any department, which wanted to start environmental physics courses a website was opened with a detailed description (www.nat.vu.nl/envphysexp, click student experiments). More information can be found in the appendix to this paper. Conclusion Environmental physics is a broad subject. As it deals with problems caused by the interaction of man and nature, it has connections with virtually all parts of physics and many of the other natural sciences. One therefore cannot ‘do research’ in environmental physics. As physicists we can do research in climate physics, nuclear physics, reactor science, biophysics and so on. When one wants to connect that with social and political problems, one is entering a field outside the physicists’ expertise, a field, which may be outside the realms of science, a field perhaps where no proven methodology does exist. Physicists have the duty to discuss the social and political implications of their work, but have to do that with more modesty than in the physics. We conclude that environmental physics is a teaching concept. The analysis of environmental problems with the aim to mitigate or prevent them, is a way to select parts of physics, relevant to society and interesting by itself. The emphasis on modelling in the teaching, the integration of many physics topics and its connections with the other natural

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sciences makes environmental physics representative for much that the professional physicist will encounter in his or her daily work. Appendix: A student lab in environmental physics

Piet Blankert and Jan Mulder2 In the framework of teaching environmental physics at the Free University of Amsterdam (VUA) six experiments in environmental physics have been developed. As these experiments are incorporated in the student labs for physics majors, first a short overview is given of the set-up and methodology of the student labs in general. Overview of the student labs In the undergraduate laboratories at the VUA, physics major students are prepared for their master research work by 8 laboratory courses. Four short courses, distributed over the years, train in writing a report, giving an oral presentation, and the application of electronics, data-analysis and automation. The four main courses concern experiments in physics and have as central teaching goal the development of students' research skills. The aims of these courses, with an emphasis on the first, (a), are: a) To acquire insight into setting up, performing and interpreting an experiment, so that students are able to follow a methodical approach to solve an experimental problem. b) To obtain knowledge about apparatus and measuring methods. c) To observe a number of physical phenomena and their relationships. In the physics experiments students are trained to follow the steps of the research cycle: 1. To translate the experimental problem into measurable quantities 2. To justify the choice of an experimental method 3. To execute measurements 4. To handle and analyse the experimental results 5. To draw conclusions Students’ research skills are gradually built up following two lines: 1- The practical instructions are not cook-book like. The courses have an open character. In subsequent courses, the focus shifts to more of the aims (a), (b) and (c). 2- During the courses in the first two years the guidance is close. In the third year it is more remote, in order to develop students’ independence in doing research. Each experiment has three formal moments of guidance: Exploratory discussion. Emphasis lies on guidance of the students. Students are working on step 1 of the research cycle, mentioned above, while the tutor gives feedback. Work plan discussion. Halfway through the research cycle (steps 2 and 3) the student takes the initiative. The student shows how (s)he will set up the experiment, and which choices are made. 2

Piet Blankert ([email protected]) and Jan Mulder ([email protected]) are staff members of the VUA students labs.

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Report discussion. In the report students show how they master also steps 4 and 5 of the research cycle. The discussion is an evaluation of the whole experiment by student and assistant together. The role of the tutor develops from guide to sparring partner to evaluator. Environmental physics experiments At the student’s lab the following environmental physics experiments were developed, keeping in mind the character of environmental physics, discussed in the main paper: • Determine the Hydraulic Conductivity of a sample • Determine the Thermal Conductivity of Sand • Heat transfer by Radiation and Convection • Laser Doppler Anemometry The velocity of a fluid is measured by means of the Laser Doppler method. In particular the radial velocity profile of the flow in a cylindrical tube can be determined. •

Radon in the Environment The amount of radon gas exhaled by different materials can be determined by measuring the timedependent radon daughter concentrations.

•

Laser Remote Sensing The wavelength- and time-dependent fluorescence of the photosynthetic system of green plants can be monitored at a distance. This results in some basic information on fluorescence and on the process of, which could give some indication about the health of green plants.

The experiments on the web (www.nat.vu.nl/envphysexp) In order to make the information about the experiments available to others the description of the experiments was put on the web (www.nat.vu.nl/envphysexp, click student experiments). The information is organised in such a way that it should be possible to copy these experiment in any physics department. Therefore, the relevant theory; a detailed description of the experimental set-up, the measurement procedures, the signal processing and the data-analysis are given. In order to make it possible to test the equipment at other labs, an example experiment, following the 5 steps of the research cycle, is worked out in a ‘cook-book’ manner. In this way the environmental experiments are somewhat different from the usual set-up described above. In order to develop the students’ research skills, more emphasis than usual is given to possible related experiments, and to theoretical and experimental problems the students may encounter and try to solve. In the teacher section information is given about the way a specific experiment fits in the VUA curriculum, how students should be guided and what problems the students may encounter with hints of their solution. Furthermore information is given about the maintenance, the required software and the total costs to set-up the experiment. References [1] Egbert Boeker and Rienk van Grondelle, Environmental Physics, Second edition, John Wiley & Sons, Chichester, 1999 (First Edition 1995). [2] Egbert Boeker and Rienk van Grondelle, Environmental Science, Physical Principles and Applications, John Wiley and Sons, Chichester, 2001

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[3] Nigel Mason and Peter Hughes, Introduction to Environmental Physics, Planet Earth, Life and Climate, Taylor and Francis, London, 2001 [4] Barret Ripin, Preparing Physicists for a life’s work, Physics Today, April 2001, 43-48 [5] Thomas Appelquist and Donald Shapero, Physics in a New Era, Physics Today, November 2001, 34-39 [6] William C. Sailor, David Bodansky, Chaim Braun, Steve Fetter and Bob van der Zwaan, A Nuclear Solution to Climate Change?, Science 288, 19 May 2000, 1177-1178 [7] Hans Spoelder and Egbert Boeker, The usefulness of visualisation: two cases from physics education, Proceedings of theFifth IASTED International Conference Computer Graphics and Imaging, M. H. Hamza, Ed., ACTA Press, Anaheim, CA, USA, August 2002, 220-225

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