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  2. Underwater vision - Wikipedia

    en.wikipedia.org/wiki/Underwater_vision

    Underwater vision is the ability to see objects underwater, and this is significantly affected by several factors. Underwater, objects are less visible because of lower levels of natural illumination caused by rapid attenuation of light with distance passed through the water. They are also blurred by scattering of light between the object and ...

  3. Electromagnetic absorption by water - Wikipedia

    en.wikipedia.org/wiki/Electromagnetic_absorption...

    Liquid water and ice emit radiation at a higher rate than water vapour (see graph above). Water at the top of the troposphere, particularly in liquid and solid states, cools as it emits net photons to space. Neighboring gas molecules other than water (e.g. nitrogen) are cooled by passing their heat kinetically to the water.

  4. Solar radio emission - Wikipedia

    en.wikipedia.org/wiki/Solar_radio_emission

    The frequency drifts from higher to lower values because it depends on the electron density, and the shock propagates outward away from the Sun through lower and lower densities. By using a model for the Sun's atmospheric density, the frequency drift rate can then be used to estimate the speed of the shock wave.

  5. Total internal reflection - Wikipedia

    en.wikipedia.org/wiki/Total_internal_reflection

    Some of the space above the water level can be seen through "Snell's window" at the top of the frame. When standing beside an aquarium with one's eyes below the water level, one is likely to see fish or submerged objects reflected in the water-air surface (Fig. 1). The brightness of the reflected image – just as bright as the "direct" view ...

  6. Photosynthetically active radiation - Wikipedia

    en.wikipedia.org/wiki/Photosynthetically_active...

    Radiation reaching a plant contains entropy as well as energy, and combining those two concepts the exergy can be determined. This sort of analysis is known as exergy analysis or second law analysis, and the exergy represents a measure of the useful work, i.e., the useful part of radiation which can be transformed into other forms of energy.

  7. Optical depth - Wikipedia

    en.wikipedia.org/wiki/Optical_depth

    Spectral optical depth in frequency and spectral optical depth in wavelength of a material, denoted and respectively, are given by: [1] = (,,) = ⁡ = (,,) = ⁡, where Φ e , ν t {\displaystyle \Phi _{\mathrm {e} ,\nu }^{\mathrm {t} }} is the spectral radiant flux in frequency transmitted by that material;

  8. Sun - Wikipedia

    en.wikipedia.org/wiki/Sun

    The Sun is 1.4 million kilometers (4.643 light-seconds) wide, about 109 times wider than Earth, or four times the Lunar distance, and contains 99.86% of all Solar System mass. The Sun is a G-type main-sequence star that makes up about 99.86% of the mass of the Solar System. [26]

  9. Brightness temperature - Wikipedia

    en.wikipedia.org/wiki/Brightness_temperature

    Nonthermal sources can have very high brightness temperatures. In pulsars the brightness temperature can reach 10 30 K. [9] For the radiation of a helium–neon laser with a power of 1 mW, a frequency spread Δf = 1 GHz, an output aperture of 1 mm 2, and a beam dispersion half-angle of 0.56 mrad, the brightness temperature would be 1.5 × 10 10 ...