hipparchus invented the latitude and longitude grid system.
hipparchus invented the latitude and longitude grid system.
who invented the latitude and longitude grid system?
hipparchus
the first rigorous system of latitude and longitude lines is credited to hipparchus. he employed a sexagesimal system that was derived from babylonian mathematics. the meridians were sub-divided into 360°, with each degree further subdivided into 60 (minutes). to measure the longitude at different locations on earth, he suggested using eclipses to determine the relative difference in time. the extensive mapping by the romans as they explored new lands would later provide a high level of information for ptolemy to construct detailed atlases. he extended the work of hipparchus, using a grid system on his maps and adopting a length of 56.5 miles for a degree.
geography
the fluid equations for agcms are made discrete using either the finite difference method or the spectral method. for finite differences, a grid is imposed on the atmosphere. the simplest grid uses constant angular grid spacing (i.e., a latitude / longitude grid). however, non-rectangular grids (e.g., icosahedral) and grids of variable resolution are more often used. the lmdz model can be arranged to give high resolution over any given section of the planet. hadgem1 (and other ocean models) use an ocean grid with higher resolution in the tropics to help resolve processes believed to be important for the el niño southern oscillation (enso). spectral models generally use a gaussian grid, because of the mathematics of transformation between spectral and grid-point space. typical agcm resolutions are between 1 and 5 degrees in latitude or longitude: hadcm3, for example, uses 3.75 in longitude and 2.5 degrees in latitude, giving a grid of 96 by 73 points (96 x 72 for some variables); and has 19 vertical levels. this results in approximately 500,000 "basic" variables, since each grid point has four variables ("u","v", "t", "q"), though a full count would give more (clouds; soil levels). hadgem1 uses a grid of 1.875 degrees in longitude and 1.25 in latitude in the atmosphere; higem, a high-resolution variant, uses 1.25 x 0.83 degrees respectively. these resolutions are lower than is typically used for weather forecasting. ocean resolutions tend to be higher, for example hadcm3 has 6 ocean grid points per atmospheric grid point in the horizontal.
general circulation model