| Caption: |
Stages in the development of an extratropical cyclone: (a) Air masses, moving in opposite directions along a front, such as the stationary front shown here, provide the temperature contrast for cyclone development; (b) a wave forms along the front at a place where upper-level winds diverge, such as a bend in the jet stream; (c) a surface low-pressure center develops as cold air pushes south on the west side and warm air pushes north on the east side of the cyclone; (d) the cold front advances faster than the warm front, catches up with the warm front, and displaces the warm air upward; (e) an occluded front develops with warm air held aloft by cold and cool air masses at the surface; (f) temperature contrast at the surface disappears, friction slows winds, and atmospheric pressure rises as the cyclone dissipates. (After Lutgens, F. K., and Tarbuck, E. J. 2007. The atmosphere; An introduction to meteorology, 10th ed. Upper Saddle River, NJ: Pearson Prentice Hall) |
| Keywords: |
atmosphere, midlatitude cyclones, middle-latitude cyclones, air masses, cyclogenesis, warm fronts, cold fronts, occluded fronts |
