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model

a way of representing the properties of an object or system

coordinate system

the system for determining the coordinates of a point

latitude

the angular distance north or south of the equator

equator

the parallel on Earth midway between the geographic north and south poles with a latitude of zero

longitude

the angular distance east or west of the prime meridian

meridian

any semi circle on earth surface connecting the north and south geographic poles

prime meridian

the meridian of zero longitude

field

any region of space or the environment that has some measurable value of a given quantity at every point

isolines

the varying values of a field represented on maps to connect points of equal field values

contour lines

isolines that connect points of equal elevation

gradient

the rate of change from place to place within the fields (slope)

gradient formula

change in amount of field value/ change in horizontal distance

topographic map (contour map)

a commonly used model of the elevation fields of the surface of earth

elevation

the vertical distance of height above or below sea level

profile

the side view of an areas landscape