Weather and climate models do not represent the atmosphere in a continuous manner, but at either discrete points or "area" averages. This is the case in the horizontal (east-west and north-south), vertical and in time. In general, models cannot represent variability on scales smaller than those defined by these discrete points or "area" averages.
Horizontal
In the horizontal the discrete points are arranged in a two dimensional grid and hence are referred to as grid points. The grid can be regular or irregular. An example of a regular latitude/longitude grid would be where the grid points are located every 1 degree of longitude in the east-west direction and every 1 degree of latitude in the north-south direction. Each grid point is associated with an area that either surrounds the grid point or lies between the grid points. This area is referred to as the "grid box".
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