ESS124
Prof. Jin-Yi Yu
Upper-Level  Front
C:\Documents and Settings\Bob\Desktop\Work\Book-Edition 3\E3 Chapter 09 Airmasses and Fronts\E3 Chapter 09 Final Figures\E3 CH9 Gifs with copyright\Fig.9.09.jpg
•Air masses do not necessary extend to the surface of the Earth.
•Air masses can be “stacked” in the vertical, so that an air mass boundary (i.e., front) can be present aloft.
•This type of front is called “cold front aloft” or “upper-level front”.
•Upper-level fronts are common feature within cyclones that form east of the Rockies.
• Upper-level fronts develop when the air from the west of the trough (which goes through adiabatically descending) meets the air from the east of the trough (which goes through moist adiabatically ascending).