2. An immense body of air that is characterized by similar temperatures & amts. of moisture at any altitude As air masses move the characteristics of an air mass change and so does the weather in the area over which the air mass is moving.

3. Source region – the area over which an air mass gets its characteristics of temperature & moisture Named according to their source region In addition to their overall temperature, air masses are classified according to the surface over which they form

4. Continental Polar (cP) – dry cool Continental Tropical (cT) – dry warm or hot Maritime Polar (mP) – form over water, cold Maritime Tropical (mT) – form over water, warm or hot

5. Much of the weather in N. America, esp. weather E of the Rockies, is influenced by continental polar (cP) & maritime tropical (mT) air masses

6. AIR MASS FOLDABLE

8. When 2 air masses meet, a front is formed. Front is a boundary that separates 2 air masses Fronts can form btw any 2 different air masses Fronts are often associated with precipitation

9. Classified according to the temperature of the advancing front 4 types: Warm, Cold, Stationary, Occluded Warm Front Forms when warm air moves into an area formerly covered by cooler air Red line with red semicircles that point toward the cooler air

11. Cold Front Forms when cold, dense air moves into a region occupied by warmer air Shown by blue line edged with blue triangles that point toward the warmer air Advance quicker than warm fronts do

13. Stationary Front The flow of air on either side of a front is neither toward the cold air mass nor toward the warm air mass. It is about parallel to the line of the front In that case the front does not move

15. Occluded Front When an active cold front overtakes a warm front Develops as the advancing cold air wedges the warm front upward Weather associated is typically complex

17. Low pressures are shown by the letter L Middle-latitude cyclones are big centers of LP that generally travel W to E and cause stormy weather Air moves in a counter-clockwise direction & in towards the center Pg. 567-68 How does a Cyclone form? Bring on stormy weather

18. Plays an important role in maintaining cyclonic & anticyclonic circulation. More often than not, air high up in the atmosphere fuels a middle latitude cyclone

20. A storm that generates lighting & thunder Produce gusty winds, heavy rain, & hail Forms from a single cumulonimbus cloud and only affects a small area OR by a cluster of cumulonimbus clouds and impact a larger area US experiences about 100,000 a year Form when warm, humid air rises in an UNSTABLE environment

21. Violent windstorms that take the form of a rotating column of air called a vortex. The vortex extends downward from a cumulonimbus cloud Form in association w/ severe thunderstorms (developing a mesocyclone) Mesocyclone – a vertical cylinder of rotating air that develops in the updraft of a thunderstorm SPC (Storm Predication Center) monitors different kinds of severe weather

22. Whirling tropical cyclones that produce winds of at least 119 km per hr. Most form btw 5 – 20 degrees N & S latitude Develop most often in the late summer when water temp. are warm enough to provide the necessary heat & moisture to the air The center is known as the eye Can cause storm surges Weakens when it moves over cool oceans AND even greater when it moves over land Category 1-5