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| | THE GREENHOUSE EFFECT |
 | "OK, Lou! First things first! If you want to understand global warming and whether or not people have anything to do with it, you need to understand the Greenhouse Effect!" |
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 | "Lay it on me Lulu! What's the Greenhouse Effect?!" |
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| "Well, you know how when you go into a greenhouse in the daytime, even in the middle of winter, it's quite warm inside, even when there's no artificial heating system!" |
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| "I'm just a city boy, Lulu! What do I know from greenhouses? Although my Aunty Tilly was thinking of having one installed...." |
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| "You get the same effect in a car, Lou! If you're sitting in a car with the windows closed on a bright day in January, even when the heat is turned off, it can be comfortably warm! Look at these diagrams and you'll see why!" |
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| "First, you need to understand that when energy in the form of light hits a pane of clear glass, almost all of the light passes through the glass! But when energy in the form of heat hits the glass, very little of the heat can get through! In other words, the glass is highly transparent to light, but almost opaque to heat!" |  |
| "Next, you need to understand that when light hits a dark object, much of the light gets absorbed and changed into heat! So light falling on an object warms it up! The heated up object then can raise the temperature of whatever is around it!" |  |
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| "Now we can put these two ideas together to understand what happens in a box with glass walls - whether it's a car or a greenhouse!" |
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| "Light enters the glass box, is absorbed by the interior objects, converted to heat, and warms the objects up! The warmed objects then heat the air inside the box! The heat can't escape easily because it has difficulty passing through the glass! Eh voila!" |
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| "You really explain things in terms a guy can understand! But what's that got to do with global warming?!" |
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| 1 - Solar Energy | 2 - Earth's Atmosphere |
| 3 - Light passes through the atmosphere |
| 4 - Absorbed light warms Earth's surface |
| 5 - Heat from warmed surface trapped by greenhouse gases; warms atmosphere |
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| "Well, the earth's atmosphere is like glass! The air is pretty transparent with respect to light! So, much of the light from the sun passes through the atmosphere, is absorbed by the earth's surface, and converted to heat. The warmed surface materials then emit heat into the atmosphere. However, because of the greenhouse gases it contains (water vapor, carbon dioxide, methane, etc.), the atmosphere (like glass) is fairly opaque to heat - and traps the heat. The trapped heat then raises the temperature of the atmosphere, producing 'global warming'!" |
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| "I get it! Like a greenhouse! Or my car! And the greater the amount of greenhouse gases in the atmosphere, the greater the 'trapping' of the heat! So, if people add to the greenhouse gases in the atmosphere, the temperature goes up!" |
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| "That's the hypothesis, Lou! But like any hypothesis, it requires testing! And that's what we're going to do next!" |
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