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  2. Water table - Wikipedia

    en.wikipedia.org/wiki/Water_table

    The slope of the water table is known as the “hydraulic gradient”, which depends on the rate at which water is added to and removed from the aquifer and the permeability of the material. The water table does not always mimic the topography due to variations in the underlying geological structure (e.g., folded, faulted, fractured bedrock).

  3. Optical window - Wikipedia

    en.wikipedia.org/wiki/Optical_window

    The optical atmospheric window is the optical portion of the electromagnetic spectrum that passes through the Earth's atmosphere, excluding its infrared part; [10] although, as mentioned before, the optical spectrum also includes the IR spectrum and thus the optical window could include the infrared window (8 – 14 μm), the latter is ...

  4. CfA 1.2 m Millimeter-Wave Telescope - Wikipedia

    en.wikipedia.org/wiki/CfA_1.2_m_Millimeter-Wave...

    The observing season for the 1.2 m telescope, like other millimeter-wave telescopes at temperate northern latitudes, generally runs from October to May, with the best conditions in November through March. Cold, dry days afford the best observations, because of the decreased atmospheric opacity due to water vapor and the colder sky in general.

  5. Atmosphere of Earth - Wikipedia

    en.wikipedia.org/wiki/Atmosphere_of_Earth

    Total atmospheric mass is 5.1480 × 10 18 kg (1.13494 × 10 19 lb), [36] about 2.5% less than would be inferred from the average sea-level pressure and Earth's area of 51007.2 megahectares, this portion being displaced by Earth's mountainous terrain. Atmospheric pressure is the total weight of the air above unit area at the point where the ...

  6. Opacity - Wikipedia

    en.wikipedia.org/wiki/Opacity

    Opacity is the measure of impenetrability to electromagnetic or other kinds of radiation, especially visible light. In radiative transfer , it describes the absorption and scattering of radiation in a medium , such as a plasma , dielectric , shielding material , glass, etc.

  7. Radio window - Wikipedia

    en.wikipedia.org/wiki/Radio_window

    Opacity of the Earth's atmosphere: the radio window spans larger wavelengths. The radio window is the region of the radio spectrum that penetrate the Earth's atmosphere . Typically, the lower limit of the radio window's range has a value of about 10 MHz (λ ≈ 30 m); the best upper limit achievable from optimal terrestrial observation sites is ...

  8. Atmospheric window - Wikipedia

    en.wikipedia.org/wiki/Atmospheric_window

    The windows are themselves dependent upon clouds, water vapor, trace greenhouse gases, and other components of the atmosphere. [ 8 ] Out of an average 340 watts per square meter (W/m 2 ) of solar irradiance at the top of the atmosphere, about 200 W/m 2 reaches the surface via windows, mostly the optical and infrared.

  9. Vadose zone - Wikipedia

    en.wikipedia.org/wiki/Vadose_zone

    Cross section showing the water table varying with surface topography as well as a perched water table The vadose zone (from the Latin word for "shallow"), also termed the unsaturated zone , is the part of Earth between the land surface and the top of the phreatic zone , the position at which the groundwater (the water in the soil's pores) is ...