Air Masses

• Chapter 8
• Mult. Choice question

Air Masses

• Mult. Choice answer:
• An air mass is an immense body of air
• 1000 miles or more across, and maybe several ____________ thick
• characterized by ______________ physical properties (especially temp and moisture)

Air Masses

• Air masses originate in a certain area, called a "______ ______" but can move to different regions while maintaining much of their original characteristics
• An ideal ______ ______ has an extensive and uniform _____ (flat land or large body of water) and __________ atmospheric conditions (high pressure areas)

Air Masses—Fig. 8-2

Air Mass Classification

• There are two letters used to identify an air mass
• The first letter describes moisture content and is either "c" for ____________ (low humidity) or "m" for __________ (high humidity) (Notice lower-case)
• The second letter describes temperature and is either "P" for ______, "A" for arctic, or "T" for ________ (Notice upper-case)
• This gives us five air mass types: cP, cA, cT, mP, and mT (there is no mA)

Air Mass Types--Fig. 8-3

 Air Mass Types

• cP: ____________ ______
• originates in ________
• cold and ____ in winter; relatively _____ and dry in summer
• brings us below freezing temps in winter; refreshingly cooler temps in summer

Air Mass Types

• cA: ____________ ______
• originates over Arctic ice caps—______ of cP region
• very cold and dry; _______ than cP
• brings us frigid weather in winter—arctic outbreak a few times per winter
• temps ______ _____ °F, could last for a week or more

Air Mass Types

• cT: ____________ __________
• originates in ________, SW US
• hot, ____ air
• common only in ________; usually stays in source region
• however, it can be advected northward and give the Southern Plains __________

Air Mass Types

• mP: __________ ______
• originates in _____ ocean waters of Pacific or Atlantic
• _____, moist air that brings precip to coasts in winter, but _________ temps in summer
• We in the Midwest are _______ affected by mP air masses

Air Mass Types

• mT: __________ __________
• originates in Gulf of Mexico and _____ ocean waters off coasts
• _____, moist air that is responsible for most of our _________ throughout the year
• In addition, gives us _____ ______ in summer—the oppressive ____, _______ conditions

Precip from Gulf of Mexico—Fig. 8-9

Air Masses Clash

• Boundaries between air masses are usually marked with ______ (e.g. _____ _______)
• Along the boundaries we find the largest _____ __________ and most unstable conditions
• Once a new air mass moves into the area, _______ conditions resume