S104 EXPLORING SCIENCE PDF
Exploring Science - DOWNLOADABLE PAPER. This paper will be provided in PDF format for you to save to your computer (please note, Adobe Acrobat reader . Faculty: Faculty of Science, Technology, Engineering and Mathematics. Keyword (s): S, Exploring science, Undergraduate course, Open University, Science. [image-0 large right]]] Exploring science (S) is a wide-ranging module that introduces important scientific concepts and develops the skills needed to study.
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ebook_s_book1_e2i1_n_l3 - Ebook download as PDF File Download as PDF, TXT or read online from Scribd S Exploring science. S Introduction and Guide - Download as PDF File .pdf), Text File .txt) or read online. On behalf of the module team, welcome to S Exploring science. Common KnowledgeSeriesOU S Exploring Science Life by D. Butler, Book 5. Exploring Earth's History by Steve Drury, Book 6. Quarks to Quasars by.
This qualitative exploratory study has limitations. First, the low number of participants does not allow generalization of results since we did not reach a complete saturation of the data. However, this is an exploratory study and the results show the importance of better understanding and fostering the integration of the interprofessional collaboration for residents.
There is a potential for representativeness bias in our sample: the participants may have had an interest for the subject of the interprofessional collaboration and it is possible that this influenced their behavior. In addition, the fact that actors were used to play the role of professionals may have an impact on the dynamics of the discussion.
Participants may indeed have behaved differently with real experienced professionals. Yet, our results open up future avenues for research aimed at better understanding and fostering the integration of the collaborative role in resident identity.
More specifically, it can contribute to the reflection on the collaborative role as proposed by the Can-MEDS physician competency framework, particularly with the addition of milestones in the version of the framework.
Footnotes The authors report no conflicts of interest in this work. References 1. Med Teach. Public health as a catalyst for interprofessional education on a health sciences campus. Am J Public Health. Frank JR, editor. The determinants of successful collaboration: a review of theoretical and empirical studies.
J Interprof Care. Horder J. Centre for the Advancement of Interprofessional Education. Center for Advancement of Interprofessional education. The effectiveness of interprofessional education: key findings from a new systematic review. Beyond curriculum: embedding interprofessional collaboration into academic culture. Multi-professional education in diabetes. Learning for real life: patient-focused interprofessional workshops offer added value.
Med Educ. Impact of a collaborative interprofessional learning experience upon medical and social work students in geriatric health care. A systematic review of the effectiveness of interprofessional education in health professional programs.
Name Meaning mean surface temperature the surface temperature at some location or over some region. This indicates that in ten years. Or is this small variation typical for this sort of data? To answer these questions requires a consideration of the history of variation in annual GMST values.
Is a rise of 0. Changes in the GMST can be measured quite accurately.
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Some measurements had to be discarded as unreliable. The English meteorologist Gordon Manley — painstakingly collated and interpreted many thermometer readings and general diary entries on weather conditions see. In this section you will look at data from one area over relatively recent history. The documents describing Figure 3. The outdoor and indoor temperatures are listed in the third and fourth columns respectively. Standardising the data to produce values that can be considered representative and comparable from year to year took very careful assessment.
The oldest records he had to deal with comprised diverse readings from different places. Viewed as a whole. You should be able to recognise that: Individual data points are not plotted. The data lie between about 8 degrees Celsius and The mean temperature of 9. The figure shows a graph of annual mean surface temperature in units of degrees Celsius on the vertical axis. The mean temperature is indicated as a horizontal line at 9. Although the temperature record of central England is unaffected by urban heat islands.
The more reliable data for later years are thought to be good to the nearest 0. Daily temperatures representative of central England are available from onwards.
So what does the temperature record of central England reveal? The scale on the vertical axis goes from 7. Instead the data are drawn as a line which continuously varies.
The data covers the period from to Before most of the data are below the mean level. As you saw above. Individual data points are shown as well as a smooth trend line through the data. The change from the value to the value therefore amounts to 0. The most obvious features brought out by the smoothed curve in Figure 3. The figure shows a graph of the annual global mean surface temperature. Concentrate for now on the individual data points in Figure 3. Deciding precisely when the fluctuations end and the warming begins is open to debate.
Although the trend is one of overall warming since The scale on the vertical axis goes from minus 0. There are years between and A data set refers to a collection of data. As in Figure 3. Near the Equator. The data shown in Figure 3. Activity 3. There are no comments on this activity. Might episodes of warming such as those happening now have been common over the last few million years? The answer to this question requires information about ancient temperatures.
This page will give you the most up-to- date data available. Before moving on to look at the distant past.
You now have an up-to-date record of the recent variation in GMST. Plot points for the more recent data you obtained from the course website onto Figure 3. Do this by carrying out the next two tasks.
The reasons for this are less obvious. You can plot more recent data than on this graph see Activity 3. Although located in what is now a desert. This information is obtained by investigating fossils. This process is climate was wetter when the how the plants produce their seeds. So there is a need to know what plants existed in various places at various times in the past. Thus the fossilised trees in Figure 3. One of the best indicators of what the temperature of a region of the Earth was in the distant past is given by the vegetation that inhabited the region.
Many plants shed pollen alive million years ago. A fossil is evidence of any ancient animal or plant. Some plants thrive in hot and humid conditions e. The spring and summer air becomes heavily trees were alive. But is this unusual compared with what might have occurred in the distant past?
This returns to the main thread of this section. Because plants produce huge numbers of pollen grains. The climate at the time the pollen was produced can then be inferred. Can you identify any of the pollen grains? Do you different types of tree. Samples of different ages are obtained by taking samples from different depths below the surface of a peat bog or lake bed.
By collecting a series of pollen samples of different ages from a given area or site. Pollen grains can be deposited in the silt Scots pine accumulating on the bottom of lakes or in peat accumulating in bogs and become preserved as fossils.
In the case of the peat bog. Book 1 Global Warming laden with pollen as people who get hay fever know well and a mature tree can produce many tens of millions of pollen grains each year. The scale think that the local trees included oak and Scots pine. Compare their shapes with those shown in the drawing of various pollen grains from pollen grains in Figure 3.
Now is a good time to A slight confusion can arise because the SI unit of mass remind you of the use of prefixes. Consider the is the kilogram, symbol kg. So it seems reasonable to number next to the scale bar in Figure 3. However, it never is: For tonne being used with SI prefixes too. However, when dealing with geological time i.
So, the Earth is 4. Likewise on the lake bed, the most recently deposited silt covers previously deposited layers of silt.
So, by boring down into the deposits a column, or core, of material can be extracted, which gives a layer-by-layer record of sedimentation and pollen accumulation over time Figure 3. The deeper the sample in the core, the older it will be.
The age of a sample, in years, is worked out using specialist techniques, but it is the results rather than the dating techniques that are of interest here.
The scale is marked in centimetres; the section of core visible is about 14 cm long. Evidence of changing climate is indicated by changes in the proportion of different pollen types throughout the core sample.
A good example of these fossil pollen investigations is the data from the bed of a lake at Hockham Mere in Norfolk, UK. Rather than displaying the data as lists of numbers in a table, it is easier to see trends when the data are plotted as a graph. This is shown for the Hockham Mere data in Figure 3. This sort of figure is called a pollen diagram.
This way of plotting data is unusual, the vertical axis increasing in value down the page the opposite of how graphs usually appear. However, this is useful as core samples are being considered which increase in depth as they go down into the ground. So at greater depths, which happen to be for periods approaching 10 years ago, birch pollen was dominant.
However, at shallower depths i. These changes were brought about by changes in the local climate over the last 10 years. In fact, there was a significant warming over this period, which favoured the growth of trees such as oak and alder. To extend this sort of pollen diagram analysis further back in time simply requires core samples that penetrate into older layers i.
One of the most remarkable core samples, providing a record over the past years, is from Grande Pile in the Vosges region of eastern France. A depth of 8 m corresponds to approximately 10 years ago. The amounts are the percentage of all tree pollen in the sample. Each pollen diagram has depth in units of metres on the vertical axis, and the amount of the tree pollen as a percentage of the total of all tree pollen on the horizontal axis.
The vertical axis starts at zero metres at the top and descends to eight metres at the bottom, so indicating the percentage of a tree pollen found at a specific depth in the core. The data are shown as a continuous curve, with the area between the curve and the vertical axis shaded. Although this shading is not required to read the data, it tends to aid easier visual comparison between pollen diagrams. The data show that below a depth of about six metres, birch pollen dominates, being greater than fifty percent and reaching about 90 percent at seven metres.
Above a depth of six metres, that is, more recent layers, birch declines and oak and alder become more important. Scots pine and elm are significant between about four and six metres depth. The difference trees. The results can then be applied in reverse, starting with a mix of plants found in an ancient pollen sample derived from pollen diagrams for many types of plant and inferring the temperatures appropriate for those plants.
Applying these techniques, the year pollen record from Grande Pile has been converted into the year record of long-term mean temperature shown in Figure 3. Note that the results are shown as a shaded band rather than a thin line. This is because there is considerable uncertainty in estimating an accurate temperature for each pollen sample, and so the result is expressed as falling within a likely range of temperatures i. This convention conveys the idea that information about older times is more deeply buried in the original core.
This means that the numbers read from the vertical The data are shown and rock fragments produced by the grinding action of the glacier leave tell-tale as a shaded band indicating signs that there has been glaciation in a region. The transitions between cold and warm periods occurred over relatively short timespans — within 30 about 10 years or so — and so these were periods of relatively rapid temperature change.
The reconstructed temperature history of the Grande Pile region Figure 3. The total collection of glacial and interglacial periods constitutes an ice age.
Is this 60 value higher. The the landscape features when the glaciation took place. This was a glacial period. The gap in the record is relatively cold conditions during the same interval. The horizontal axis shows that temperature increases to the right. Recent times.
It is also possible to use fossil The figure shows age on the vertical axis extending from zero down to thousand years ago. This has revealed that in the last 2. U-shaped valleys carved out by temperature cannot be the passing glacier and glacial till and moraines mounds or sheets of boulders calculated. The data are shown as a thick shaded band. This overall mean value is considerably lower than 90 the recent mean temperature of 9. Temperatures during the warmer periods were similar to those 20 of today.
This is estimated by imagining a vertical 80 line such that as much of the temperature data lies to the left of the line as to the right of the line. Book 1 Global Warming scale must be multiplied by years: The left figure vertical scale goes from the present day down to million years ago. The times when history Figure 3.
This is a challenging question but. Looking back at Figure 3. The horizontal axis represents temperature but is simply labelled as colder than or warmer than the present day.
The figure shows two diagrams side by side. These lie at between about to million years. The frozen landscape of eastern Figure Greenland is so cold that a permanent ice sheet is present. Four periods of major ice ages are shown as shaded horizontal bands. Note that the when the record is reasonably last 2. The data show that the past million years have generally been warmer than the present day. Note that the vertical time axis counts backwards from the major ice ages occurred present day to the very earliest history of the Earth the units being Ma — millions are identified by the blue of years.
In order to understand exactly why this might be occurring. In Book 6 you will look at some past temperature variations in more detail. Why is the level of carbon dioxide that human activity is pumping into the atmosphere such big news.
It appears then that the recent global warming is indeed unusual. This recent rate of warming appears to be unusual compared to what occurred in the past. Historical records ignoring variable urban heat island effects indicate an irregular rise in the annual GMST over the past years or so. Over long periods.
One aspect that needs to be considered when answering this question is the rates of increase in temperature. Look back at Figure 3. Thus the current temperature increase on Earth is about five times greater than seems to have occurred in the past. If 30 consecutive years are averaged the effects of unusual years are reduced and long-term trends are emphasised. Earlier in this chapter you calculated the GMST increase within the last years or so.
You will do this in the following chapters. Measurements should be quoted to an appropriate number of significant figures. When reading from a scale on a piece of experimental equipment such as a thermometer. The most recent glacial period ended about 10 years ago. Throughout this ice age. You have considered types of uncertainty. Records of fossil plant pollen can be used to estimate the mean temperature at the time the plants were alive.
Fossil pollen from different depths in cores taken through peat bogs and lake beds reveals how the proportions and identities of the plants changed through time.
The longest continuous pollen record is from France and spans the last years but. You have plotted data on a graph. Measurements with small random uncertainties are said to be precise. This reveals that we are living in an ice age that started some 2. You have used SI units with various prefixes.
When energy is transferred to an object. One joule 1 J is a small amount of energy: Energy can be measured and. Power is a word that is often used in everyday life in all sorts of contexts. If you are in any doubt. When you are outside on a sunny day and turn your face to the Sun. When you burn gas under a pan of water. Although there are very many forms of energy. There are many manifestations of energy. At the most basic level. The symbol for the joule is J. You need to understand how the Earth gains energy from the Sun.
This can be expressed as an equation: At no point is it possible to create energy or destroy energy — it can only be transferred.
Energy is a physical property possessed by an object. These are all examples of energy transferring from one type to another. Power is the rate at which energy transfer takes place. One of the most familiar is that associated with heat.
The SI unit of energy is the joule. At this stage. Imagine you have a map with a scale such that 1 cm on the map represents 1 km in reality i. What about if you had a stick. Book 1 Global Warming Box 4. It could also be written as: Could you write the following? You might know what you meant but. Written as an equation.
You are no doubt happy that everything balances. An equation is only valid when the two sides are balanced i. Thus an equation says that one quantity is equal to another quantity. The equation is still saying that all the terms on the left in this case.
You should take care with units in an equation. You then measure a distance of. As you know each cm represents 1 km in reality. The use of units was revised in Box 2. The correct way of expressing this is to write 9 cm on the map is equivalent to 9 km in reality. A good analogy is a set of old-fashioned balancing scales: The SI unit of time is the second.
The watt is exactly made major improvements to the the same unit as that used in specifying the power requirements of electrical design of steam engines.
For now they will be grouped together to give one overall rate of energy loss to give the highly simplified picture in Figure 4. The arrows are of equal widths. You are now ready to consider the various rates of energy transfer — the rates of energy gain and loss — that determine the GMST. A typical microwave oven might have a power rating of W. The arrow representing energy gain points down into the surface.
Hence a typical electric kettle might have a rating of 2. Often it is appropriate to quote large values of power in kilowatts kW. This means in one second the energy transferred is J. All other sources of energy are negligible — the next largest is the energy that flows out from the interior of the Earth. The energy transferred per second is given by: The use of prefixes with units was revised in Box 3. This analogy will help you understand how the system works — in this sense. This is a pictorial way of showing that the rates of energy gain and loss in Figure 4.
If you wanted to direct someone to a particular office. Note that the width of the downward pointing arrow is equal to that of the upward-pointing arrow. Scientific models aid understanding by focusing only on some important aspects of the system. In this context. Book 1 Global Warming The downward-pointing arrow in Figure 4. If the rates were not equal. Figure 4. The sketch is more usable than the photograph. To explore the relationship between the GMST and the rates of energy gain and loss in more detail.
A direct and important consequence of this equality is that the GMST is constant. This is why. The surface would cool to a lower GMST. The important components of reality the roads. East Campus.
If so, you will know the maps are helpful but, again they are only models of reality. The distance between stations and the actual geographical locations of stations are not realistic i. However, the most important information the order of stations along the lines, and at which stations lines connect is retained in the maps. If you required the precise layouts of roads and buildings, you would need to use a geographically accurate map. Even that map is not reality — it is just another model, but a model with somewhat different priorities.
In other words, you might use different models of the same thing for different purposes. Although the examples given here have focused on maps, a model can take many forms. Look again at Figure 4. You should now realise that this treatment of the balance of energy gains and losses is itself a model of the real world system.
Clearly, this is not like reality, but it is a model of reality that represents the main components in an understandable way. In Chapter 8 you will use a specific type of model — a mathematical model run on a computer — to predict changes in GMST values. The analogy is a leaky tank into which water is pouring. The level of water in the tank represents the GMST: In the leaky tank shown in Figure 4.
The greater the depth of water in the tank, the greater the rate of water loss from the slot. Initially, the leak rate is less than the rate of input, so the water level rises. The leak is through the rectangular slot at the side of the tank. As the water level rises, there is a greater length of slot to let the water out, so the leak rate increases, and it continues to increase until the leak rate equals the rate of water input.
At this point, the water level stops rising, and it stays at the level it has reached. The water level is now in a steady state, i. Of course, water is pouring into and out of the tank, so this is a dynamic steady state rather than a static steady state. The crucial condition for the dynamic steady state is that the input and output rates are equal. This equality of rates can be expressed as: You can see that in the first 10 seconds after the tap is turned on, the water level rises from zero to about 17 mm.
In the time interval 10 to 20 seconds after the tap is turned on, it rises from 17 to about 30 mm, i. Reading from the graph in Figure 4. Thus, as the water level rises, the rate at which the level changes decreases i.
In the graph this is apparent from how the curve bends over. You can see that, ultimately, the curve flattens out and stays at the same water level — the steady-state level.
At this constant level, the leak rate equals the rate of input. The water level rises until the leak rate equals the rate time for scenarios a , b and of input, whereupon the level becomes steady.
The three graphs, labelled A, B and C, correspond to the behaviour of the water level in the tank that was shown in figures 4. All three graphs have axes extending from zero millimetres to eighty millimetres on the vertical axes, and zero to seconds on the horizontal axes.
The figure shows nine photographs of a transparent water tank. The water tank is positioned below a tap that is feeding water into the tank at a rate which depends on how hard the tap is turned on.
However, the tank has a thin vertical slot cut in the centre of a side face, with the slot running from the bottom to near the top of the tank such that water can leak out of the slot. The top three photographs form figure A, representing three steps in increasing time.
The middle three photographs form figure B, again representing three steps in increasing time starting from a different starting condition. Similarly the bottom three photographs form figure C. If the tap is now turned on harder to increase the input rate, the water level starts to rise again. The leak rate increases until a new steady state is reached, with a higher water level Figure 4. The graph in Figure 4. Now, returning to the original steady state at the end of the sequence in Figure 4.
The leak rate is now greater that the input rate, so the water level falls. This reduces the leak rate until another steady state is reached, this time at a lower water level Figure 4.
The graph shows this level to be about 25 mm. Note that these graphs do not have quantitative scales on the axes. If it is widened. Returning to the leaky tank. This would normally be a critical failing of a graph.
So by modelling the behaviour of the system in this way. This corresponds to the situation illustrated in Figure 4. If the slot is narrowed. For now. The reasons for this relationship between GMST and energy loss rate are explored later in the chapter.
Activity 4. Book 1 Global Warming Figure 4. The GMST then rises until the loss rate equals the new rate of gain. The higher the GMST. In Figure 4. Your description in each case should consist of several sentences. The rate of energy transfer is lower than the old steady state.
As you will see in the next section. With the aid of Figures 4. The rate of energy transfer is higher than the old steady state. The width of each arrow represents the rate of energy transfer. Now look at the comments on this activity at the end of this book. There are several completely different types of radiation that come from the Sun. Note that ultraviolet and infrared are often abbreviated to UV and IR. Human eyes are sensitive to only the visible radiation light but if you could see light of a shorter wavelength.
It is emitting red light but it is also emitting a lot of infrared radiation. This is why infrared cameras allow the world to be seen even in total darkness. When the element of an electric cooker is turned up to full. It also shows in which direction the wavelength property increases longer wavelengths and decreases shorter wavelengths. The light that is visible to humans can be split into different colours as in a rainbow.
This is just one part of a very broad range of light-type radiation you will consider the full range in detail in Book 3. The figure shows the colours of the rainbow contained in visible light and also infrared and ultraviolet radiation.
From right to left the colour labels read. Radiation in general terms means something that spreads out radiates from a source. This is why the information on creams to prevent sunburn often refers to UV filters. The direction of shorter and longer wavelengths — ultraviolet UV radiation and infrared IR radiation — are also shown. Although UV radiation is not visible. The colours on the right are labelled longer wavelength and the colours on the left are labelled shorter wavelength.
Book 1 Global Warming 4. Like everything else. This side can be represented as a disc-shaped area facing the radiation Sun. The radiation leaving the Sun spreads out in all directions.
The rate at which solar radiation intercepted falls on this area is obtained from measurements taken by radiation sensors on satellites orbiting the Earth.
This is a mean value over many years. This power is called the solar luminosity. An area of one square metre 1 m2 facing the Sun as in Figure 4. An mentioned above. The total solar radiation intercepted by bottom of the diagram receives the Earth can then be calculated from: In other words. Returning to solar radiation: The Sun is far more powerful: This average value is called the solar constant.
The SI unit for the rate of transfer of any form of energy is the watt. A large power station generates about W of electrical power.
In figure D the arrows extend vertically down to the surface but do not bounce off the surface. In figure C the arrows extend vertically down to the surface and bounce off the surface. Four scenarios are shown.
Series: OU S104 Exploring Science
To see why. Clouds are particularly good at scattering. In figure A the radiation arrows extend vertically down and stop within the atmosphere. The aerosol spray from a can consists of tiny liquid droplets. Atmospheric dust is another example of an aerosol.
Some escapes back to space. The essential feature of absorption is that solar radiation is ultimately converted into heat. Scattered radiation travels in all directions. In figure B the arrows extend vertically down but then each hit a point in the atmosphere which causes the arrow to change direction. An aerosol is a collection of tiny typically micrometre- sized liquid or solid particles dispersed in a gas. Scattering and absorption occur throughout the atmosphere.
Other arrows. In the oceans this happens throughout the top few tens of metres of water.
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Ice and snow reflect most of it. The width of each solar radiation arrow indicates approximately scattered by the relative rate of energy atmosphere transfer. The word albedo is derived from the Latin word albus. Some of this radiation is scattered from the surface Figure 4.
This is usually called reflection. There is a thick arrow extending from the top of the diagram.
You can see from Figure 4. Different types of surface reflect different proportions of solar radiation. Just as in the atmosphere. The mean rate at which solar radiation is returned to space by the combined effects of scattering and reflection.
The pattern is represented by arrows. Now suppose that the situation in Figure 4. This is the transfer of heat from a region of higher temperature the base of the pan to a region of lower temperature the bottom layer of water because of the direct contact between the two regions. This heats the base of the pan. Consider a pan of water at room temperature standing on a switched- off electric hot-plate.
The unit of volume is m3 and thus the unit of density must be kg. The figure shows two diagrams of a pan of water on a hot plate. The base of the pan in turn heats the thin layer of water in contact with it.
There is no upward or downward motion in the water. Density is defined as the mass per unit volume of a substance. In the first figure. In the second figure. The water in this layer is heated by a process called conduction.
A steady cycle is set up. Having touched on thermal expansion. This is basically because no extra mass of water is being added to the ocean — the water is already there as ice.
If ice sheets that are sitting on top of land as in Greenland and Antarctica were to melt. The rise in the temperature of the thin layer of water causes it to increase in volume. Note that its mass is fixed.
In principle this could happen in several different ways. It could happen on a microscopic scale. This is called thermal expansion. Ice melt has certainly had a great effect in the past when ice ages have ended and vast numbers of mountain glaciers have melted and deposited huge amounts of water into the oceans.
From Equation 4.
S104 Introduction and Guide
As mentioned in Chapter 2. The fact the ice rises up above the surface of the ocean does not matter. This is simply a result of the ice being less dense than water. Melting of ice does have an effect. It will rise back to the surface. From experience. Fluid flow driven by temperature differences is called convection. Many people assume that this is caused only by ice melting.
If this displaced volume were actually occupied by the surrounding water. The rising air loses energy to its surroundings. Book 1 Global Warming To clarify this. It looks similar to that of the heated water in figure 4. This pattern can exist on scales that.
Cooler air is displaced downwards. This is sometimes referred to as the volume of water displaced by the iceberg. The effect of hot air rising is used by balloonists. Some birds also use thermals for lift. When the whole iceberg melts. For the GMST. Warm air rises. Glider pilots call them thermals. This is why floating ice cubes melting in a jug of water do not alter the level of the water as they melt.
Columns of convection are so gentle that they usually go unnoticed. Atmospheric convection can often be seen as the shimmer or heat haze from the heated air rising from a hot surface such as a road in sunlight Figure 4. This answers the first of the questions posed at the beginning of Chapter 1. This is a physical requirement of floating. Through this process. The burner heats the air enclosed by the balloon canopy to the point where it becomes sufficiently Figure 4.
Warm air rises up. You will be familiar with this effect. This cooling effect is caused by the moisture requiring latent heat i. This is an important point that has consequences for the greenhouse effect — you will return to this in Chapter 8. The higher the temperature.
Try dampening the palm of your hand with a liquid. Returning to the moist air that. When this maximum is reached. The source of this surface water is not just seas and lakes and rivers but any moisture at the surface. This is because the amount of water vapour that air can contain is related to the temperature of the air.
If the relative humidity is. This energy is called latent heat. Evaporation requires energy to be transferred to the liquid or ice in order to produce the water vapour. Another way of saying this is that. The amount of water vapour that can be held in the air at its saturation point i. Convection carries this water vapour upwards.
This involves the evaporation of liquid water to produce water vapour i. As it rises. The evaporation of sweat in a strong wind also produces obvious cooling. This is because the latent heat has been extracted from the material.
If the temperature falls low enough. While the water undergoing a change of state does not change its temperature. Air heated by the ground rises up through the atmosphere. Ice can change state directly from solid to water vapour by a process called sublimation. The latent heat energy given out by condensation heats the surrounding atmosphere. Precipitation from the atmosphere returns water to the ground i.
Book 1 Global Warming If it takes an input of heat to produce vapour from liquid or solid. Question 4. When the water vapour condenses. The rest ultimately reaches the ground and thus constitutes another energy gain by the surface.
The two other arrows originate in the atmosphere. They are absorbed solar radiation. This is because all of the four energy gains by the atmosphere depend on solar radiation: The upward-pointing arrow represents the rate at which infrared radiation emitted by the atmosphere escapes to space.
This arrow splits into two. The atmosphere then re-emits infrared radiation. The width of each arrow indicates approximately the rate of energy transfer. The time has come to put them all together and obtain an overview.
At the extreme right three connected arrows. The convective and latent heat transfers are also included. The key points can be summarised as follows. To develop this ability. In the next activity you will reinforce your understanding of Figure 4.
The lines represent the energy transfers between the different boxes. Your task is to add the labels to the other lines. This is a flow diagram and such diagrams are a particularly useful way of summarising information. To help you. Try to do this at first without referring to Figure 4. You will meet many examples of flow diagrams throughout the course and you will develop further. Now you will examine the case of the solar constant. The arrows that require labels are as follows.
Arrows connect the various boxes representing the energy transfer processes between the items in the boxes. The figure shows four boxes with labels in them. If any of these factors is changed. Thus there are eight arrows in total that require labelling. If a factor changed. The other arrows are not labelled and activity 4.
This graph shows the value being constant. The vertical axis of the top graph shows the value of the solar constant in units of watts per metres squared. At the instant that the solar constant changed. If there were no atmosphere.
The solar constant does indeed vary. Recall that the value quoted earlier Section 4. The presence of an atmosphere complicates the situation because the surface also receives infrared radiation from the atmosphere.
What would happen? At once. There would then be a new steady state. This is basically the situation in the leaky tank analogy in Figure 4. All three graphs are plotted with time along the horizontal axes. The solar constant varies by only about 0. Suppose that initially there is a steady state with the Sun shining as it does today when. This is represented by the top graph in Figure 4. Note that the solar constant axis does not start at zero.
The vertical axis of the middle graph shows global mean surface temperature in units of degrees Celsius. This rise in GMST would cause the surface to emit more infrared radiation. The middle and bottom graphs show how the quantities vary as a result of the sudden change in solar constant shown in the top graph. The figure shows three graphs. There would be a steady state.
This warms the surface. This effect. The ground then emits infrared radiation. Some of this infrared radiation is emitted back into the greenhouse the rest being radiated outwards to the outside world. Earth does have an atmosphere. This leads to a higher steady-state GMST than there would be without an atmosphere. This chapter concludes by considering just one more — the effect on the GMST of changing the rate at which the atmosphere absorbs and emits infrared radiation.For any value can be rewritten as a number that is equal example.
Even that map is not reality — it is just another model, but a model with somewhat different priorities. This topic is obviously of great interest and concern. In studying this chapter.
To ensure the units work out correctly within calculations.
International Journal of Climatology. Support Find your personal contacts including your tutor and student support team: Hewitson, D.
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