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ESS124
Prof.
Jin-Yi Yu
Typical Environment
Prior the Cyclone
•A cold, dry airmass over Canada and the northern US
•A warm, humid airmass over the southern and eastern US
•A warm, dry airmass over the higher elevations of the western US and Mexico
•A cool moist airmass over the noreastern US and Canada.
•This four-airmasses model
may vary from season to season and day to day.
•A fifth airmass originates
in the upper troposphere, and is tyoically found aloft, and its leading edge is the “upper-levele
front”.