An object can also reflect EM energy, as when visible light bounces off a mirror. Microwave ovens use this interaction to cook food: substances such as water and fat absorb microwave energy (which has a long wavelength) and heat up as a result. As it happens, when you canРІР‚в„ўt see blue and violet, the world appears amber-colored.Matter can interact with electromagnetic energy in several ways. We can only see the colors that reach our eyes. Amber-tinted sunglasses are transparent to red, orange, yellow, and green light, but absorb blue and violet light. This is because sunglass lenses do not transmit every wavelength of visible light. When we wear sunglasses, we see everything with a tint. Within that range are bands that correspond to different colors of light (in order of decreasing wavelength: red, orange, yellow, green, blue, and violet). For example, the wavelength of visible light ranges from 390 to 700 nanometers. Some objects will absorb one kind of energy while allowing other kinds to pass right through them. Which of these interactions occurs depends on three factors: the objectРІР‚в„ўs elemental composition, its molecular structure, and the energyРІР‚в„ўs wavelength. The filament in an incandescent light bulb, on the other hand, gets so hot when you turn it on that it glows with visible light, which has a shorter wavelength. For example, humans and other animals are only warm enough to give off infrared energy, which has a relatively long wavelength and is invisible to the naked eye. Warmer objects give off energy with short wavelengths, while cooler objects give off energy with long wavelengths.

The kind of energy they emit depends on how hot they are. All objects give off electromagnetic energy of some kind. If the earth suddenly started receiving more energy from the sun-or if less of the energy it did receive was able to escape back into space-its overall temperature would go up. This is as true on a planetary scale as it is in your living room. By using the fire to add extra energy to the room, you are increasing its overall temperature. But if you build a fire in that fireplace, the heat that it gives off will warm you and the rest of the room. If you sit in front of an empty fireplace, youРІР‚в„ўll only be as warm as the room around you. The more energy it absorbs, the hotter it gets and the more energy it emits. How hot an object is, and thus how much energy it emits, depends on how much energy it absorbs from its surroundings. The key difference between the two is that visible light has a shorter wavelength than infrared energy. As far as the greenhouse effect goes, the two kinds of EM energy that we are most interested in are visible light (sunlight), and infrared energy (a kind of heat). Wavelength is important because it determines how various kinds of EM energy interact with matter. Ripples that are very close together have a short wavelength, while more widely spaced ripples have a long wavelength.

The wavelength of the ripples is the distance from the top of one ripple to the top of the next ripple. Different kinds of EM energy have different wavelengths, which can be visualized as ripples on the surface of a pond. EM energy travels in the form of a wave-that is, it fluctuates between РІР‚СљpeaksРІР‚Сњ where its electromagnetic field is strongest, and РІР‚СљtroughsРІР‚Сњ where it is weakest. Light from the sun, microwave energy, radio waves, and even heat-all things we encounter on a daily basis-are types of electromagnetic energy. Electromagnetic EnergyР”В®lectromagnetic (EM) energy may sound exotic, but itРІР‚в„ўs actually very common. It occurs because the earth and the sun give off different kinds of electromagnetic energy, and because CO 2 and other greenhouse gasses absorb one kind (from the earth) while allowing the other (from the sun) to pass through them. Without it, life on earth would not be possible. Certain gasses in our atmosphere, such as CO 2, methane, and water vapor, absorb and РІР‚СљrecycleРІР‚Сњ some of the sunРІР‚в„ўs energy, keeping earth much warmer than the sun can by itself. In reality, earthРІР‚в„ўs average surface temperature is a much more comfortable 58РІВРЏ. Earth only gets enough energy from the sun to warm its surface to about 0РІВРЏ-pretty warm compared to outer space, but still far too cold for life to exist. Without its atmosphere, earth would be one giant snowball. Second, CO 2 acts as a greenhouse gas, absorbing heat from the earth and preventing it from escaping out into space. First, plants and other photosynthesizing organisms pullit out of the air and combine it with water to create carbohydrates, which are the foundation of the food chain. It has two major environmental functions. Structurally, a CO 2 molecule is pretty simple: one carbon atom with an oxygen atom on either side.

While that might no t seem like a lot, it still comes out to more than three trillion tons of CO 2 floatingР’В around in the air. Carbon dioxide makes up about 0.04% of our atmosphere.

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