lecture notes 8

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Published on 10 Oct 2011
School
UTSG
Department
Geography
Course
GGR100H1
(Lecture 07)
Weather Chap 8 , Feb03/2011
Key points
Mechanisms for air parcel lifting and consequences for the weather
Role of air masses
Why it’s important: links between weather and ecosystems, human
activity
Weather: The big picture
Principle regional air masses for N. America
Moisture and temperature characteristics
mT =Moisture: maritime (wet) or continental (dry) Temperature: Arctic,
polar, or tropical
Movement of air masses
Air masses take on local temperature/humidity
Snow belts
Effect of moving air mass on local weather
Weather: the details
What causes an air parcel to lift?
Convergent lifting
Convectional lifting
Orographic lifting
Frontal lifting
*Convergent lifting (picture 6-12)
Convectional lifting
Warmer surfaces
Flow of air from maritime à continent
Local heating
Unstable parcels
Clouds, precipitation
Orographic lifting
Air forced upslope
Frontal lifting
Front = edge of advancing air mass
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Document Summary

Key points activity: mechanisms for air parcel lifting and consequences for the weather, role of air masses, why it"s important: links between weather and ecosystems, human. Principle regional air masses for n. america: moisture and temperature characteristics, mt =moisture: maritime (wet) or continental (dry) temperature: arctic, polar, or tropical. Movement of air masses: air masses take on local temperature/humidity. Effect of moving air mass on local weather. What causes an air parcel to lift: convergent lifting, convectional lifting, orographic lifting. Front = edge of advancing air mass: density/temperature differences lead to lifting along margin (= edge) Advancing cold front abrupt lifting: wind shift, drop in barometric pressure, heavy precipitation, thunder, due to, as cold front passes, higher pressure, lower temperatures, clearing clouds. Advancing warm front: gentle lifting lower density of warm vs. cold front, drizzly precipitation. Storm tracks: upper air winds, regional names. Lightning (electrical discharge within clouds, clouds-ground) superheated air thunder: microbursts.