The gal (symbol: Gal), sometimes called galileo after Galileo Galilei, is a unit of acceleration typically used in precision gravimetry.[2][3][4] The gal is defined as 1 centimeter per second squared (1 cm/s2). The milligal (mGal) and microgal (µGal) are respectively one thousandth and one millionth of a gal.
gal
Earth's gravity measured by NASA GRACE mission, showing deviations from the theoretical gravity of an idealized smooth Earth, the so-called earth ellipsoid. Red shows the areas where gravity is stronger than the smooth, standard value, and blue reveals areas where gravity is weaker. (Animated version.)[1]
Gravity anomalies covering the Southern Ocean are shown here in false-color relief. Amplitudes range between −30 mGal (magenta) to +30 mGal (red). This image has been normalized to remove variation due to differences in latitude.
The gal is not part of the International System of Units (known by its French-language initials "SI"). In 1978 the CIPM decided that it was permissible to use the gal "with the SI until the CIPM considers that [its] use is no longer necessary".[3][5] Use of the gal was deprecated by the standard ISO 80000-3:2006, now superseded.
The gal is a derived unit, defined in terms of the centimeter–gram–second (CGS) base unit of length, the centimeter, and the second, which is the base unit of time in both the CGS and the modern SI system. In SI base units, 1 Gal is equal to 0.01 m/s2.
The acceleration due to Earth's gravity (see Standard gravity) at its surface is 976 to 983 Gal, the variation being due mainly to differences in latitude and elevation. Mountains and masses of lesser density within the Earth's crust typically cause variations in gravitational acceleration of tens to hundreds of milligals (mGal). The gravity gradient (variation with height) above Earth's surface is about 3.1 µGal per centimeter of height (3.1×10−6 s−2), resulting in a maximal difference of about 2 Gal (0.02 m/s2) from the top of Mount Everest to sea level.[6]
Unless it is being used at the beginning of a sentence or in paragraph or section titles, the unit name gal is properly spelled with a lowercase g. As with the torr and its symbol, the unit name (gal) and its symbol (Gal) are spelled identically except that the latter is capitalized.
^NASA/JPL/University of Texas Center for Space Research. "PIA12146: GRACE Global Gravity Animation". Photojournal. NASA Jet Propulsion Laboratory. Retrieved 30 December 2013.
^Barry N. Taylor, Guide for the Use of the International System of Units (SI), 1995, NIST Special Publication 811, Appendix B.
^ abBIPMSI brochure, 8th ed. 2006, Table 9: Non-SI units associated with the CGS and the CGS-Gaussian system of units 2007-10-18 at the Wayback Machine.
^Some sources, such as the University of North Carolina 2012-02-18 at the Wayback Machine, the European Space Agency, and ConversionTables.com 2009-05-19 at the Wayback Machine state that the unit name is "galileo". The NIST and the BIPM are here considered as more authoritative sources regarding the proper unit name.
^NIST Guide to SI Units; Section 5, Units Outside the SI; Subsection 5.2: Units temporarily accepted for use with the SI.
^Gravity Measurements 2009-03-06 at the Wayback Machine. University of Calgary. Accessed Nov 21, 2009.
July 21, 2023
unit, confused, with, gallon, symbol, sometimes, called, galileo, after, galileo, galilei, unit, acceleration, typically, used, precision, gravimetry, defined, centimeter, second, squared, milligal, mgal, microgal, µgal, respectively, thousandth, millionth, ga. Not to be confused with gallon The gal symbol Gal sometimes called galileo after Galileo Galilei is a unit of acceleration typically used in precision gravimetry 2 3 4 The gal is defined as 1 centimeter per second squared 1 cm s2 The milligal mGal and microgal µGal are respectively one thousandth and one millionth of a gal galEarth s gravity measured by NASA GRACE mission showing deviations from the theoretical gravity of an idealized smooth Earth the so called earth ellipsoid Red shows the areas where gravity is stronger than the smooth standard value and blue reveals areas where gravity is weaker Animated version 1 General informationUnit systemCGS unitsUnit ofAccelerationSymbolGalNamed afterGalileo GalileiConversions1 Gal in is equal to CGS base units 1 cm s2 SI units 0 01 m s2 Imperial US customary 0 03280840 ft s2Gravity anomalies covering the Southern Ocean are shown here in false color relief Amplitudes range between 30 mGal magenta to 30 mGal red This image has been normalized to remove variation due to differences in latitude The gal is not part of the International System of Units known by its French language initials SI In 1978 the CIPM decided that it was permissible to use the gal with the SI until the CIPM considers that its use is no longer necessary 3 5 Use of the gal was deprecated by the standard ISO 80000 3 2006 now superseded The gal is a derived unit defined in terms of the centimeter gram second CGS base unit of length the centimeter and the second which is the base unit of time in both the CGS and the modern SI system In SI base units 1 Gal is equal to 0 01 m s2 The acceleration due to Earth s gravity see Standard gravity at its surface is 976 to 983 Gal the variation being due mainly to differences in latitude and elevation Mountains and masses of lesser density within the Earth s crust typically cause variations in gravitational acceleration of tens to hundreds of milligals mGal The gravity gradient variation with height above Earth s surface is about 3 1 µGal per centimeter of height 3 1 10 6 s 2 resulting in a maximal difference of about 2 Gal 0 02 m s2 from the top of Mount Everest to sea level 6 Unless it is being used at the beginning of a sentence or in paragraph or section titles the unit name gal is properly spelled with a lowercase g As with the torr and its symbol the unit name gal and its symbol Gal are spelled identically except that the latter is capitalized Conversions EditConversions between common units of acceleration Base value Gal or cm s2 ft s2 m s2 Standard gravity g0 1 Gal or cm s2 1 0 0328084 0 01 1 01972 10 31 ft s2 30 4800 1 0 304800 0 03108101 m s2 100 3 28084 1 0 1019721 g0 980 665 32 1740 9 80665 1See also EditEarth s gravity Eotvos unit g force g Gravimetry Gravity Gravitational constant G Gravitational field Gravity gradiometryReferences Edit NASA JPL University of Texas Center for Space Research PIA12146 GRACE Global Gravity Animation Photojournal NASA Jet Propulsion Laboratory Retrieved 30 December 2013 Barry N Taylor Guide for the Use of the International System of Units SI 1995 NIST Special Publication 811 Appendix B a b BIPM SI brochure 8th ed 2006 Table 9 Non SI units associated with the CGS and the CGS Gaussian system of units Archived 2007 10 18 at the Wayback Machine Some sources such as the University of North Carolina Archived 2012 02 18 at the Wayback Machine the European Space Agency and ConversionTables com Archived 2009 05 19 at the Wayback Machine state that the unit name is galileo The NIST and the BIPM are here considered as more authoritative sources regarding the proper unit name NIST Guide to SI Units Section 5 Units Outside the SI Subsection 5 2 Units temporarily accepted for use with the SI Gravity Measurements Archived 2009 03 06 at the Wayback Machine University of Calgary Accessed Nov 21 2009 Retrieved from https en wikipedia org w index php title Gal unit amp oldid 1163202894, wikipedia, wiki, book, books, library,
