Absorption and Re-Radiation Lab Name: _ E.N. Read the Power of the Albedo Effect on Global Warming article and define the following items below: http://www.greenoptimistic.com/2013/07/30/the-power-of-the-albedo-effect-on-global-warming/#.ux3jlf5dhr4 The Power of the Albedo Effect on Global Warming By Leigh Hutchens July 30, 2013 Climate Change Albedo is the percentage of incoming radiation reflected off a surface. The term comes from the Latin word for whiteness. When applied to the Earth, the albedo effect measures how much of the sun s energy is reflected back into space. The balance between energy absorbed by the earth and energy reflected back into space is important in determining how warm or cool the planet becomes. Albedo can range between 0 (no reflectance) and 1 (complete reflectance -like a mirror). The average albedo of the Earth is.31, meaning the planet reflects about 31% of incoming solar radiation back into space. However, forests and deserts, oceans, clouds, snow, and ice all have different albedos, and changes in them can affect how much solar radiation the earth receives. For example, the albedos of forests lie in the range 0.07 0.15, while deserts have an albedo of around 0.3. According to experts, global albedo is pretty stable and consistent and has no effect on global temperatures, but local effects of albedo might be more pronounced. The albedo effect makes ice melting a non-linear process. Loss of albedo in the Arctic could heat the water sufficiently to release methane stored in ice crystals. Few people realize that methane is a greenhouse gas that is far more potent than CO2 since it s more efficient at trapping radiation. Accelerated warming across adjacent permafrost will happen with the loss of albedo in the Arctic, which will then release methane. Reduced Arctic albedo will also accelerate ocean warming, melting the edges of the Greenland ice cap, speeding up sea level rise. Albedo: Methane: What will happen if albedo is reduced? In this experiment we will see how the color of an object affects its ability to absorb visible radiation, and then to give off invisible heat radiation. You will be recording the temperatures of the two cans as they absorb and then lose heat. (You may be surprised by part of the results.) Materials: 2 cans; 1 black, 1 silver, Foam covers for cans, 2 metal backed thermometers Lamp with reflector Books to rest cans on ½ meter stick
Procedure: 1. Find two thermometers that read the same Celsius temperature. Then set up the apparatus as shown above. The two cans should be only 2-3 cm apart. Be sure that the two cans are at the same height as the light bulb, and that each can is exactly 15 cm from the light bulb. Don t turn it on yet. 2. Record the initial temperatures of both cans in the 0 min. boxes below. (Ask your teacher to check your setup before you turn on the light.) 3. Record the two temperatures each minute for 10 minutes while the lamp is on. 4. Without disturbing the cans, turn the map off and slide it away after exactly 10 minutes. Continue taking the temperatures for another 10 minutes as the cans cool off. 5. Construct a graph of your data. This graph will have two best fit lines on one graph, one line for the silver can and one for the black can. Each line will go up for the first ten minutes, and then down for the last ten minutes. You can start your graph while you are recording the cooling data. Problem: Predict the effect of deforestation on climate (temp. change) in regions usually covered in snow. Hypothesis: Time (min) Black Silver 1 2 3 4 5 6 7 8 9 10 *** off 11 12 13 14 15 16 17 18 19 20 Claim: Evidence at last two sources Reasoning
A. Which color (black or silver) absorbs electromagnetic energy best? B. According to your graph, which color cools off fastest? (Note which line is steeper) C. On a cool, sunny day, which color would keep you the warmest? D. Which of these colors is best to wear to keep cool in the summer? E. What color of car is the most practical in keeping a comfortable temperature? This color should keep cool on sunny summer days and warm of cloudy winter days. Please explain your answer. F. What other factor, besides color, seems to affect the rate of cooling? (Your cooling line should become less steep as time passes. Why does this happen? You may know that the Earth receives nearly all of its energy as insolation. But the Earth also radiates energy back into space. If it did not, the Earth would become constantly hotter and hotter. The balance between the insolation absorbed and the heat energy lost to space keeps the climate of our planet moderate. G. Is heat radiation visible to our eyes? H. How can the person in the top diagram to the left tell that the iron is radiating energy? The earth absorbs mostly visibly light. The energy radiated into space is mostly long wave heat energy known as infrared radiation. I. According to the second diagram, what happens to the wavelength of energy when it is absorbed by the Earth and then re-radiated? J. What would happen to the Earth if it did not lose as much energy as it absorbs?
The graph to the right shows the radiation given off by the sun and the radiation that reaches the Earth s surface. It also shows the infrared (heat) radiation that the Earth loses to outer space. Notice that most of the ultraviolet light is absorbed by our atmosphere. Ozone is the principal gas that protects the Earth from this dangerous ultraviolet radiation. K. According to the graph, in what part of the spectrum is insolation most intense? L. In what part of the spectrum is the radiation that reaches the ground the most intense? M. In what part of the spectrum is the terrestrial radiation lost to space the most intense? N. What color should a home radiator be painted to give off heat the best? O. What color is the best absorber and radiator of electromagnetic energy? Three Ways to Make Your Roof More Energy Efficient January 4, 2011 By Amy Westervelt Not everyone can have a living roof, but most people can have a green roof fairly easily. And the great news is that improving the energy efficiency of your roof doesn t have to be costly. Small improvements can deliver a big difference, not only to your home s energy usage, but also to the size of your energy bill.following is a series of steps, from small to large, which will help green both your roof and your home. Cool Your Roof: Cool roofs refer to roofs that are cool in both senses of the word. Lighter in color than traditional black asphalt or dark wood shingles, cool roofs save energy by reflecting light and heat away rather than absorbing both. This is known as the albedo effect, and study after study in the last few years has documented significant energy savings from simply lightening the color of a roof. The problem with dark roofs: The temperature outside may be 95 degrees, which is plenty hot, but your dark roof is conducting a much higher temperature down at you and your family, making the rooms below hotter and making the air conditioner work harder, Barbara Collins points out in her answer to the Ask A Pro question "NYC has a 'cool roof' program. Is there a white paint or coating to make my roof cooler?" In New York City, she notes, a dark- colored asphalt roof can reach 150 to 175 degrees on a hot summer day. This not only increases the energy needs of your home, it also contributes to the heat island effect in urban areas. The benefits of cool roofs: A cool roof, on the other hand, can be 50 to 60 degrees cooler than a conventional dark- colored roof, reducing the cooling load on your home, saving energy, and reducing utility costs. By decreasing the solar gain and heat retention of your home, a white roof also increases its comfort and reduces the heat island effect that your home s dark roof contributes to. How to cool your roof: The easiest route is to slap a cool roof coating onto an existing roof. Check out these recommendations from Dave Edwards, PhD, of EarthBound Homes, for coating options. If you re already re- roofing, or building a new residence, consider replacing shingles or asphalt with lighter- colored versions of themselves. If you ve got a flat- top roof, Edwards suggests DuraLast s sheets of fiber- reinforced white PVC membranes, in his Q&A "I'm reroofing a typical sloped roof - - what materials should I be considering?" A quick search of the Cool Roof Rating Council s Rated Products Directory, will provide you with performance data about various roofing products. Products are rated for their reflectiveness on a 0 to 1 scale; the higher the number, the more reflective the product is, and the cooler your roof will be.