HORIZONTAL AIRCRAFT PASSES ACROSS O-DEGREES-C REGIONS WITHIN WINTER STORMS

Seventeen horizontal aircraft passes were made across 0 degrees C regi ons within 10 winter storms over Atlantic Canada. Regions of near free zing temperatures (+/-1 degrees C) ranged from <2 km to 145 km in exte nt. These regions were associated with both warm and cold fronts. The detailed kinematic, thermodynamic and microphysical characteristics of these regions were deduced Significant changes in these characteristi cs often occur very close to 0 degrees C and indicate that these 0 deg rees C regions were often directly associated with the locations of th e fronts aloft. Microphysical processes involving phase changes of pre cipitation significantly affect the nature of the atmosphere near thes e 0 degrees C regions and in particular affect the structure of some o f the fronts.