1. A method of visualizing structured grid data on a monitor using computer graphics technology, the structured grid data including first and second structured grid data respectively arranged for first and second component structured grids of a spherical structured grid that is constituted by complementarily combining said first component structured grid and said second component structured grid to form a sphere, said first component structured grid being constituted by extracting from a latitude-longitude grid in a first spherical coordinate system a range between a certain value of −45 degrees or less and a certain value of 45 degrees or more, excluding −90 and 90 degrees, in latitude and a range between a certain value of 45 degrees or less and a certain value of 315 degrees or more, excluding 0 and 360 degrees, in longitude, said first spherical coordinate system using a z axis of an xyz space as a central axis, said second component structured grid being constituted by extracting from a latitude-longitude grid in a second spherical coordinate system a range between a certain value of −45 degrees or less and a certain value of 45 degrees or more, excluding −90 and 90 degrees, in latitude and a range between a certain value of 45 degrees or less and a certain value of 315 degrees or more, excluding 0 and 360 degrees, in longitude, said second spherical coordinate system using a y axis of the xyz space as a central axis, the method comprising the steps of: creating a first graphic object using said computer graphics technology after setting said first component structured grid in a first local xyz coordinate system used in computer graphics and disposing the first structured grid data on said first component structured grid; creating a second graphic object using said computer graphics technology after setting said second component structured grid in a second local xyz coordinate system used in said computer graphics and disposing the second structured grid data on said second component structured grid; rotating the second graphic object by 90 degrees with respect to an x axis of said first local xyz coordinate system, together with said second local coordinate system, and then rotating the resulting second graphic object by 180 degrees with respect to a z axis of said first local xyz coordinate system; and visualizing a graphic object, which has been obtained by combining the first graphic object and the rotated second graphic object, on said monitor as an image, using said computer graphics technology.