ch11 - Jon Ahlquist 12/9/2006 Chapter 11: Air Masses and...

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12/9/2006 MET1010 Intro to the Atmosphere 1 Chapter 11: Air Masses and Fronts Air mass classification Air mass source regions Air mass modification Fronts Cold Fronts “Back door” cold fronts Warm fronts Occluded fronts Dryline Air Masses: Defn and Formation (p. 286) ± Air mass: Large body of air that has similar horizontal temperature and moisture characteristics ± Air mass formation: Air must remain over a surface with nearly uniform conditions for days ± Air masses can form: ² over ocean or fairly flat land;light winds needed. ² rarely over mid-latitudes (too changeable) ² not over mountains (not uniform) ± Usually marked by regions of high pressure, where winds are weak, but may be a “heat low” Types of Air Masses (Table 11.1, p. 287) Source Region Polar (P): Cool or cold surface Tropical (T): Warm or hot surface Continental (c): Dry cP Cold, dry, stable cT Hot dry, stable aloft; unstable surface air Maritime (m): Moist mP Cool, moist, unstable mT Warm, moist; usually unstable Extremely cold cP air is called continental Arctic (cA). Coldest and hottest air masses are continental: land has greater temperature extremes than water. Air Mass Source Regions and Their Paths (fig. 11.2, p. 287) What kind of air mass is this? (Fig. 11.1, p. 286) Temp from -15 to 27 deg F Upper no. of each pair is temperature, lower no. is dew point in degrees F. Answer: At least conti- nental polar, perhaps started as continental arctic (cA). What kind of air mass is this? (Fig. 11.11, p. 295) Map for 29 June 1990 Temp from 90’s to 108 deg F Arrow marks jet stream. “H” marks position of upper-level subtropical high. Continental
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This note was uploaded on 07/21/2011 for the course MET 1010 taught by Professor Staff during the Fall '08 term at FSU.

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ch11 - Jon Ahlquist 12/9/2006 Chapter 11: Air Masses and...

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