Why Worry about Carbon Dioxide

Energy Type Wavelength Range Relative Energy 

Each type of radiation elicits a certain response when it impinges on a molecule or an object. An inspection of the relative energies associated with IR, Vis, and UV radiation reveals that IR radiation has the lowest energy of the three. IR radiation is sufficiently energetic to cause certain chemical bonds to bend or stretch but not to break. Infrared radiation is sometimes referred to as heat radiation because it causes things to warm up as the bonds comprising the molecules stretch and bend. 

That brings us to carbon dioxide, methane, and water. These gases do absorb infrared radiation because certain stretches and bends of the bonds in these molecules disrupt the electron distribution in ways necessary for IR absorption. Because carbon dioxide, water vapor, and methane are three molecules that are capable of absorbing IR radiation, these molecules play a major role in keeping Earth warm. 

Carbon dioxide s effect on temperature can be illustrated by comparing the temperature on Venus (the second planet from the Sun) to that on Earth. Both planets are warmer than can be explained simply by looking at their distance from the Sun. Venus, whose average temperature is 450°C, is estimated to be 300°G warmer than might be predicted based on its distance from the Sun. Earth, which is almost 26 million miles farther from the Sun, is still about 33°G higher in average temperature (15°C) than the — 18°C predicted. Why is that  

Use relationships between the Fahrenheit and Gentigrade temperature scales to convince yourself that 59°F, Earth s average temperature, corresponds to 15°C. Do the same to show that Venus s average temperature of 450°G is 840°F. [Relationships °F = (9/5)°C + 32 and °G = (5/9) (°F - 32)] 

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