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  2. Water table - Wikipedia

    en.wikipedia.org/wiki/Water_table

    Below the water table, in the zone of saturation, layers of permeable rock that yield groundwater are called aquifers. In less permeable soils, such as tight bedrock formations and historic lakebed deposits, the water table may be more difficult to define. “Water table” and “water level” are not synonymous. If a deeper aquifer has a ...

  3. 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.

  4. 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 ...

  5. Atmosphere of Earth - Wikipedia

    en.wikipedia.org/wiki/Atmosphere_of_Earth

    Air also contains a variable amount of water vapor, on average around 1% at sea level, and 0.4% over the entire atmosphere. Earth's early atmosphere consisted of accreted gases from the solar nebula , but the atmosphere changed significantly over time, affected by many factors such as volcanism , impact events , weathering and the evolution of ...

  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. 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 ...

  9. Standard sea-level conditions - Wikipedia

    en.wikipedia.org/wiki/Standard_sea-level_conditions

    Standard sea-level conditions (SSL), [1] also known as sea-level standard (SLS), defines a set of atmospheric conditions for physical calculations. The term "standard sea level " is used to indicate that values of properties are to be taken to be the same as those standard at sea level, and is done to define values for use in general calculations.