Chapter 8 Outline

Chapter 8 Outline - Chapter 8 Weather Weather Essentials...

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Chapter 8: Weather Weather Essentials Weather - short-term, day-to-day condition of atmos; snapshot of atmos cndtns/tech’l status report of Earth-atmos heat-energy budget; climate- long-term avg over decades of weather cdtns/extremes in a reg; impt elements in weather- temp, air press, rel hum, wind speed/direction, seasonal factors Meteorology - scientific study of atmos; phys characteristics/motions, related chem., phys, geologic processes studied; tools help eg computers, Doppler radar, Advanced Weather Interactive Processing System ( AWIPS )- allows integration of meteorological, hydrological, satellite, radar data at computer Doppler radar uses backscatter fr 2 radar pulses to detect direction of moisture droplets to measure wind direction/speed- impt to forecasting/storm warnings; weather data collection expanding; cost of weather-related destruction has risen grtly past 2 decades Air Masses Each area of Earth’s surface imparts its temp/moisture characteristics to air it touches=>reg’l masses of air have specific cdtns of temp, hum, stability; these air masses interact to=>weather patterns; air  mass initially reflects characteristics of its source region ; longer air mass stays over reg: More definite its phys traits become; w/in each air mass= homogenous mix of temp/hum Air Masses Affecting North America Air masses classified by moisture, temp characteristics of thr source regs (see pg. 209 ): o Moisture - designated m for maritime (wet), c for continental (dry) o Temperature (latitude factor)- A (arctic), P (polar), T (tropical), E (equatorial), AA (Antarctic) Continental polar (cP) air masses form only in N Hem, usu dvlpd winter when they dominate cold wthr cdtns; major in mid-/hi-lat wthr; b/c cold/dense, lifts moist, wrm air in its pth=>lifting, cooling, cdnstn; greater temp diff btwn cP/warmer air masses=>more dramatic weather Area covered by cP air in winter=>cold, stable air, clear skies, high press, anticyclonic wind flow; S Hem lacks necess landmasses to produce cont’lity at high lats to create cP chars; maritime polar (mP) air masses in N Hem exist NW/NE of N America over N oceans; in thm, cool, moist, unstable cdtns Aleutian, Icelandic subpolar low-press cells reside w/in mP air masses esp in winter; 2 maritime tropical (mT) air masses- mT Gulf/Atlantic & mT Pacific- influence N America; E/MidW hum due to mT Gulf/Atlantic- esp unstable, active late spring-early fall; mT Pacific stable-condtn’ly unstable… ~Lower in moisture content/available energy; thus W US under it gets less precipitation than rest US; W edge of Atlantic (E coast)- moist, unstable; E edge Pacific (W coast)- drier, stable; these cdtns + Air Mass Modification As air masses migrate fr source regs, thr temp/moisture chars change to adopt those of land over which they pass; eg below-freezing temps may hit S TX/FL by invading winter cP air mass fr N, but cP
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Chapter 8 Outline - Chapter 8 Weather Weather Essentials...

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