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  2. Seismic velocity structure - Wikipedia

    en.wikipedia.org/wiki/Seismic_Velocity_Structure

    Within the Earth's crust, seismic velocities increase with depth, mainly due to rising pressure, which makes materials denser. [31] The relationship between crustal depth and pressure is direct; as the overlying rock exerts weight, it compacts underlying layers, reduces rock porosity , increases density , and can alter crystalline structures ...

  3. Atmospheric pressure - Wikipedia

    en.wikipedia.org/wiki/Atmospheric_pressure

    Atmospheric pressure, also known as air pressure or barometric pressure (after the barometer), is the pressure within the atmosphere of Earth. The standard atmosphere (symbol: atm) is a unit of pressure defined as 101,325 Pa (1,013.25 hPa ), which is equivalent to 1,013.25 millibars , [ 1 ] 760 mm Hg , 29.9212 inches Hg , or 14.696 psi . [ 2 ]

  4. P wave - Wikipedia

    en.wikipedia.org/wiki/P_wave

    A P wave (primary wave or pressure wave) is one of the two main types of elastic body waves, called seismic waves in seismology. P waves travel faster than other seismic waves and hence are the first signal from an earthquake to arrive at any affected location or at a seismograph .

  5. Atmospheric circulation - Wikipedia

    en.wikipedia.org/wiki/Atmospheric_circulation

    Those cells exist in both the northern and southern hemispheres. The vast bulk of the atmospheric motion occurs in the Hadley cell. The high pressure systems acting on the Earth's surface are balanced by the low pressure systems elsewhere. As a result, there is a balance of forces acting on the Earth's surface.

  6. 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), [42] 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 ...

  7. Effects of high altitude on humans - Wikipedia

    en.wikipedia.org/wiki/Effects_of_high_altitude...

    Pressure as a function of the height above the sea level. The human body can perform best at sea level, [7] where the atmospheric pressure is 101,325 Pa or 1013.25 millibars (or 1 atm, by definition). The concentration of oxygen (O 2) in sea-level air is 20.9%, so the partial pressure of O 2 (pO 2) is 21.136 kilopascals (158.53 mmHg).

  8. Earth's inner core - Wikipedia

    en.wikipedia.org/wiki/Earth's_inner_core

    the Earth's mass, its gravitational field, and its angular inertia. These are all affected by the density and dimensions of the inner layers. [20] the natural oscillation frequencies and modes of the whole Earth oscillations, when large earthquakes make the planet "ring" like a bell. These oscillations also depend strongly on the inner layers ...

  9. Pressure gradient - Wikipedia

    en.wikipedia.org/wiki/Pressure_gradient

    The horizontal pressure gradient is a two-dimensional vector resulting from the projection of the pressure gradient onto a local horizontal plane. Near the Earth's surface, this horizontal pressure gradient force is directed from higher toward lower pressure. Its particular orientation at any one time and place depends strongly on the weather ...