In the definition of the variogram
, 
represents
a vector of modulus 
and direction 
. Consider a particular direction .
Beginning at the origin,
, the variogram
increases in general with the modulus . This is
simply an expression of the fact that, on average, the difference between
two grades taken at two different points increases as the distance
between them increases. The manner in which this variogram increases for
small values of characterizes the degree of
spatial continuity of the variable studied.