a. Sample M12.
b. Sample M6.
Figure 10. Thin sections of ice sampled during the March icing event from
a bulkhead (sample M6) and an icicle (sample M12), illustrating grains en-
circled by large channelized networks filled with brine (scales in millime-
which constitute a ready source of pictures that can be
However, to improve the resolution of the microstruc-
compared and evaluated at a moment's notice, were
ture for crystallographic examination, the sections were
used to document textural characteristics of the accreted
microtomed further until they measured 0.5 mm or less
ice (crystal/inclusion relationships) and to measure crys-
in thickness, depending on the average size of crystals
tal and inclusion sizes.
in the section. Sections were prepared both parallel and
normal to the accretion surface. A Bausch and Lomb
Crystal size measurements
extension (bellows) camera fitted with polarizers was
used to obtain structure photographs of each thin sec-
Determining crystal size in thin sections usually re-
tion. Photographs were taken at 7.5 magnification on
quires measurement of either the diameter or the cross-
sheet film measuring 17.5 12.5 cm. Contact prints,
sectional area of grains. Seligman (1949), for example,