Spatial scale provides a "shorthand" form for discussing relative lengths, areas, distances and sizes. A microclimate, for instance, is one which might occur in a mountainvalley or near a lakeshore, whereas a megatrend is one which involves the whole planet.
It is important to realize that these divisions are more or less arbitrary, and where, on this table, mega- is assigned global scope, it may only apply continentally or even regionally in other contexts. The interpretations of meso- and macro- must then be adjusted accordingly.