Science Objects are two hour on-line interactive inquiry-based content modules that help teachers better understand the science content they teach. This Science Object is the third of four Science Objects in the Nature of Light SciPack. It provides conceptual and real world understanding of how the wavelengths of electromagnetic radiation affect the way they interact with different materials. We perceive differences of wavelength within the visible part of the spectrum as differences in color. Shorter wavelengths of light (blue) are scattered more by air molecules than longer wavelengths of light (red). When the atmosphere scatters sunlight—which is a mixture of all wavelengths—short-wavelength light (which gives us the sensation of blue) is scattered much more by air molecules than long-wavelength (red) light is. The atmosphere, therefore, appears blue and the sun seen through it by un-scattered light appears reddened. Also, materials that allow one range of wavelengths to pass through them may completely absorb others. For example, some gases in the atmosphere, including carbon dioxide and water vapor, are transparent to much of the incoming sunlight but absorb the infrared radiation from the warmed surface of Earth.
Type Science Object