We analyze the morphology of network bright points (NBPs), their relation t
o fine dark mottles and their temporal variations, using observations of a
quiet region near the polar solar limb, obtained during the solar minimum.
For our analysis we used an image-processing method for the selection and i
dentification of NBPs. Further we constructed `maximum power frequency' map
s computing the power spectrum for each pixel of a field and selecting the
frequency of maximum spectral power as the most representative oscillating
frequency for this pixel. The morphological analysis of our data indicates
that the enhancement of NBPs is part of a complicated process that is respo
nsible for the formation of mottles. The analysis of the lifetimes of NBPs
indicates that although the general patterns of NBPs remain constant for ti
me intervals larger than an hour, the lifetime of individual bright points
is of the order of 16 min. Furthermore, our results indicate an association
of the lifetime of NBPs with that of mottles. From the analysis of tempora
l variations we confirm that the power of NBPs is smaller than the correspo
nding power for intra-network points at both the 3-min and the 5-min oscill
ating modes and in both the Mg b(1)-0.4 Angstrom and the continuum. Our ana
lysis revealed enhanced power in the 7-min range, which is theoretically co
nsidered a candidate frequency for transverse waves related to NBPs at the
base of the chromosphere (Kalkofen, 1997). However, we consider more likely
that this period is related to the evolution of individual NBPs.