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When infrared light of these frequencies strikes an object, the energy is reflected or transmitted. If the object is transparent, then the light waves are passed on to neighboring atoms through the bulk of the material and re-emitted on the opposite side of the object. Such frequencies of light waves are said to be transmitted. [10] [11]
Infrared (IR; sometimes called infrared light) is electromagnetic radiation (EMR) with wavelengths longer than that of visible light but shorter than microwaves. The infrared spectral band begins with waves that are just longer than those of red light (the longest waves in the visible spectrum ), so IR is invisible to the human eye.
Although water is nearly transparent in the range of visible light, it becomes absorbing over the near-infrared region. Water is a critical component since its concentration is high in human tissue. The absorption spectrum of water in the range from 250 to 1000 nm is shown in Figure 2.
The infrared atmospheric window is an atmospheric window in the infrared spectrum where there is relatively little absorption of terrestrial thermal radiation by atmospheric gases. [1] The window plays an important role in the atmospheric greenhouse effect by maintaining the balance between incoming solar radiation and outgoing IR to space.
The gaps between the bands define the infrared window in the Earth's atmosphere. [17] The infrared spectrum of liquid water is dominated by the intense absorption due to the fundamental O-H stretching vibrations. Because of the high intensity, very short path lengths, usually less than 50 μm, are needed to record the spectra of aqueous solutions.
The plastic bag is mostly transparent to long-wavelength infrared, but the man's glasses are opaque. Thermal radiation emitted by a body at any temperature consists of a wide range of frequencies. The frequency distribution is given by Planck's law of black-body radiation for an idealized emitter as shown in the diagram at top.
Researchers compressed infrared light to 10% of its wavelength using a thin strontium titanate film, paving the way for advanced infrared imaging.
Also, out of about 340 W/m 2 of reflected shortwave (105 W/m 2) plus outgoing longwave radiation (235 W/m 2), 80-100 W/m 2 exits to space through the infrared window depending on cloudiness. About 40 W/m 2 of this transmitted amount is emitted by the surface, while most of the remainder comes from lower regions of the atmosphere. In a ...