Electromagnetic Radiation and Earth's Energy Balance
Electromagnetic waves are all around us. All different kinds in all kinds of places. They allow us to see the world around us, feel the warmth of the sun on our skin, enjoy music on the radio and make popcorn in microwave ovens! But they can also be harmful, responsible for such things as sunburns, skin cancer and global warming. Here's your chance to explore the nature of electromagnetic waves...
BASIC LEVEL
Let's start off with a quick introduction (or review for those of you already familiar with this topic!) of the Electromagnetic Spectrum. This Electromagnetic Spectrum Tutorial and NASA mini-movie are great places to start! Now take a look at the Electromagnetic Spectrum and check out the different kinds of EM waves that exist. What kinds of objects are the same lengths as the smallest EM waves? What about the biggest? Do you think that there could be waves larger or smaller than these that have not yet been detected? Post answers to these and the Basic Level Questions in your eFolio.
Let's focus on Thermal Radiation and look more closely at the relationship between the temperature of an object and the energy and wavelength of EM waves it generates. First start with some interactive tutorials: Catch the Waves, Making Waves and Heating Up. Document your progress through these short tutorials as best you can. For example, you can take webshots of those pages that ask for your input and include them in your eFolio.
GRAB YOUR POINTS!
1. Log into eFolio. The link below will place your work into the eFolio and give you the Mini Survey.
GOING BEYOND
Now that you know that the properties of temperature, energy and wavelength depend on each other, you are probably wondering whether the relationships have been quantified! You bet they have! There are three famous radiation laws that were “discovered” in the late 19th century for "black body" objects.
The radiation laws are known as the Stefan-Boltzmann Law, Wien’s Law and Planck’s Law. Look them over and make sure you understand what each of these equations allows you to determine and on what factors they depend. Play with these animations (The Planck Law, Black Body Radiation Excercises, and Black Body: The Game) to gain a better understanding of the laws. In your eFolio, tell us what each of these laws mean in plain English, without using a math equation!
You are almost done! Use the radiation laws to answer the following Going Beyond Questions. Be sure to show all of your work in your eFolio.
Ludwig Boltzmann lived a very interesting, but tragic, life. Despite his amazing work in the area of theoretical physics, he committed suicide in 1906 at 62 years of age. No one really knows why, but theories have been proposed that he was either mentally ill or convinced that his theories would never be accepted (although they were proven experimentally shortly after his death!).
Here's a simple experiment you can try. On a clear dry evening after a sunny day, as the sun is setting, extend your arm out over the ground (grass, dirt, or even better a driveway or parking lot). Turn your hand over, back and forth, several times -- palm facing down, then up, then down, etc. You will be able to feel the difference in the amount of IR radiation reaching the top and bottom of your hand. The reason for this is that the sky is emitting much less infrared radiation downward than the ground is emitting upward.
GRAB YOUR POINTS!
1. Log into eFolio. The link below will place your work into the eFolio and give you the Mini Survey.
GOING CRAZY
Now that you know something about the electromagnetic spectrum and thermal radiation, let's take a closer look at how they relate to Earth's climate by looking at the impact of the sun's energy on Earth. These schematics show you what happens to the sun's energy after it enters Earth's atmosphere. Look it over closely. What kinds of things can you think of that could affect how energy is absorbed and emitted by Earth, and, as a result, alter Earth's surface temperature. (Remember that energy absorbed by a body will cause its temperature to rise. And the radiation emitted by that body will depend on its temperature, as described by the Radiation Laws.) Record your ideas in your "STEM Explorations" folder with a file titled "Electromagnetic Radiation and Earth's Energy Balance - Going Crazy".
PC Users can check out a lab that uses a Global Energy Balance Model. Mac Users can explore the Lake Mono Energy Budget Model.
GRAB YOUR POINTS!
1. Log into eFolio. The link below will place your work into the eFolio and give you the Mini Survey.
If You Need Help
If you have specific questions about this exploration, please contact your STEM Mentor. If you still have questions, email Susan Hull Grasso. Or "Skype" her:
Chat with Susan Hull Grasso, GCA Director of Curriculum Development