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Chapter 19: Weather patterns and severe storms

Terms in this set (113)

What is a large body of
air (specified moisture
content and Temperature) that
affects a large
portion of the continent.
Air masses
What are air masses characterized by?
similarity of temperature and moisture at any given latitude
What are the characteristics of air masses?
1)In southern California, were under the influence of the subtropic high

2) Convergence low creates uplift

3) Divergence high creates subsidence
What tells us what region the air masses are coming from; the area where air masses acquire its properties of temperature and moisture
Source regions
Air masses are classified according to what?
Their source region
What air masses indicate temperature?
Polar, Arctic, and tropical
What two air masses originate in high latitudes near the earth's poles?
1) Polar (P)

2) Arctic (A)
What air masses form in low latitudes?
Tropical (T) air masses
Which two air masses indicate cold?
Polar and Arctic
Which air masses indicates warm weather?
Tropical
Which air masses suggests moisture characteristics?
1) Continental air masses (dry)

2) Maritime air masses (wet)
Which air mass forms over land?
Continental air mass (C)
Which air mass originates over water?
maritime (m) air mass
In terms of air masses, what are the two classifications of moisture?
1) dry: continental (c)

2) wet: maritime (m)
In terms of air masses, what are the two classifications of temperature?
1) High: Polar (P) and Arctic (A)

2) Low: tropical (t)
Temperatures drop as air masses go where?
southward
What are the different air masses?
1) Continental Polar (cP)

2) Continental tropical (cT)

3) Continental Arctic

3) Maritime Polar (mP)

4) Maritime Tropical (mT)
What are cP, mP, cT, and mT air masses are classified according to their
source region
What air masses influence the weather in North America the most?
1) Continental Polar

2) Maritime tropical
What are the winter patterns?
1) Maritime tropical (affects weather in California)
2) Maritime polar (organ and Washington)
3) Continental Arctic (very cold, very dry)
4) Continental Polar (Cold, dry)
Any time that the air mass comes from the north
Polar
What does cP stand for?
Continental Polar
Where do Continental polar air masses originate?
Northern Canada, interior Alaska, Arctic
What are the characteristics of Continental Polar?
Cold and dry
What does mT stand for?
Maritime Tropical
Any time that the air mass comes from the south
Tropical
What are the characteristics of Maritime Tropical?
Warm and humid
Maritime Tropical air mass originate over which warm waters?
Gulf of Mexico, Caribbean Sea, or Atlantic Ocean
Maritime tropical air is the source of most of the _________ in the eastern 2/3 of the US
precipitation
Which air mass has the least influence not the weather in North America?
Continental tropical
What does mP stand for?
Maritime polar
What are the characteristics of Maritime Polar?
Cool and humid
Where does Maritime Polar air masses originate?
North Atlantic off the coast of eastern Canada; influences weather of North Eastern states like New England
What does cA stand for?
Continental Arctic
What are the characteristics of Continental Arctic?
Very cold and very dry
How can an air mass classification change?
If air mass travels across open oceans or over a large continent
What is it called when air masses travel across open oceans?
maritime classification
What is it called when air masses travel over a large continent?
Continental classification
Be able to identify the source regions of the Winter pattern
...
What is the difference between summer and winter patterns?
Summer pattern is the same as winter except no continental Arctic in the summer; but there is a Continental Tropical (hot dry)
What is an example of the fact that air classifications may change
Cp modified; cP--> mP
Which occurs when cP winds go across the great lakes during late autumn and early winter.... then air mass picks up moisture and drops snow on the leeward side of the lakes
Lake effect snow
What is the process of Lake effect snow
1) continental polar air masses cross the Great Lakes
2) Air picks up moisture from the lakes
3) snow occurs on leeward side of shores
What does Lake effect snow affect?
Michigan, NY, ext.
What is an example of Lake effect snow?
Great lakes
What result from lake effect snow?
Snowbelts
In lake effect snow, on which side of the lake does the snow accumulate?
leeward side
What is the boundary between air masses of different moisture content and temperature
Front
Within fronts, warmer less dense air is ________
aloft (up)
Within fronts, cooler, denser air acts as a ______
wedge (stays low)
Fronts are associated with _________ pressure centers generated by the ______________
low/ high; 5 air masses
The fronts in the US are driven by what?
westerlies
What are the different kinds of Fronts?
1) Warm fronts

2) Cold fronts

3) Stationary fronts

4) Occluded fronts
What is it called when warm air occupies territory formally covered by cool air?
warm front
What is the process of a warm front?
1) warm air glides over cold air; warm replaces cooler air

2. progression of
clouds--> Cirrus, cirrostratus, altostatus, nimbostratus (red semicircles in direction of warm air flow); clouds become lower as slope nears

3. Temperature goes up

4. winds from South because mT

5. gradual slope
Warm fronts produce what kind precipitation?
light to moderate rain over a wide area
What is the slope of a warm front?
1:200 (gradual slope)
What is an example of warm front?
Frontal wedging
What is the symbol for a warm front?
Semi circles in direction of warm air flow
What is the slope of a cold front?
Steep slope 1:100
What are the characteristics of a cold front?
1) cold air replace warm air

2) faster than warm front

2) severe weather; storms can develop

3) heavy precipitation

4)wedge steep, vertical towering clouds Cumulonimbus

6) Winds come from the the West/ North West because mP/cP
What is the process of a cold front?
1) cold front comes in and pushes warm air aloft
2) Cumulonimbus clouds form
3) heavy precipitation and lighting
4) as storm passes, the air is cool
The more rapid advance of a cold front causes ____________ and the formation of ________________ clouds
adiabatic cooling; cumulonimbus
What is the symbol of a cold front?
blue triangles pointing toward direction of wind flow
What is a stationary front?
1)not moving, a stalemate

2)Will have cloudy conditions (altocumulus) / sometimes rain clouds

3) overrunning
What is a nonmoving boundary between hot and cold air masses
Stationary front
What is the symbol for a stationary front?
Blue triangles on one side of the front and red circles on the other
What occurs when a cold front overtakes a warm front; cold front wedges warm air upward; (warm front gliding over cold air mass)
Occluded front
What is an occluded front associated with?
midlatitude cyclones
What is the formation of the occluded front?
1) cold front tries to catch up to warm front
2) collides and becomes occluded
3) warm air is forced up (precipitation)
4) when cold front over takes warm, the rain will lighten up
How do you determine the sequence of cloud formation in a occluded front?
look at the warm front, and then cold above; lingering cold
Where is the wind direction from in an warm front
South bc mT
Where is the wind direction form in a cold front?
West of Northwest because cP and mP
Where is the wind direction from in an occluded front?
South or Southeast (mT) --> North to Northwest
What is the difference between a warm and cold front?
1) cold air moves slower and denser so the boundary will be steep for a cold air mass

2) warm air moves up, it moves up very rapidly resulting in severe weather conditions (conditional instability)

Angle is a lot smaller in the warm air mass
Which weather map symbol has semicircles and triangles on opposite sides?
stationary
Which weather map symbol has circles on one side?
Warm front
Which weather map symbol has triangles on one side?
Cold front
What is the weather map symbol had triangles and circles on the same side?
Occluded front
What forms along a front when air masses are moving parallel to a front in opposite directions
Middle-latitude cyclone
Mid-latitude refers to what regions?
region between Florida and Alaska
Mid-latitude cyclones are associated with..
Low pressure centers (L)
Midlatitude cyclones are large centers of low pressure that travel from ______ to ______
west to east
Midlatitude cyclones have what kind of rotation?
counterclockwise; airflow inward towards center
What are the characteristics of Midlatiude cyclones?
1) 30-60 degrees

2) Move from West to east

3) Low pressure centers have a cyclonic flow (counterclockwise)
What is the process of the Mid-Latitude Cyclone?
1) The moist, warm Maritime Tropical air mass from Gulf + the Continental Polar air mass from Canada merges to develop a cyclonic flow

2) Warm and cold front develop

3) cold front overtakes warm front and occlusion begins

4) finally dissipating

5) winds form west (NW: Washington and Organ) to East
Cyclones are guided by _______________
westerlies aloft
What two air masses are responsible for midlatitude cyclones?
Maritime Tropical and Continental Polar
What front signals the end of a mid-latitude cyclone?
Occluded front
How does the CounterClock wise rotation around a low pressure center begin?
1) continual drop in air pressure

2) increasing overcast conditions that bring varying amounts of precipitation
where do the severe storm like tornados and thunderstorms occur
Coma
What air masses contribute to a Nor' easter?
1) Maritime Polar and maritime tropical

2) Occurs in NE states
What can Nor'ester be referred to as?
perfect storm
What occurs south of the low pressure cyclone?
1) approaching cyclone: cold air (cP) winds E/SE

2) progression of high to low level clouds (Ci--> Cs--> As--> Ns) as warm air mass (mT from Gulf) glides over cold air, gentle ppt. (nimbostratus)

3) Warm for a time (cumulus) winds S/SW, clear skies

4) Cb with approaching cold air, possible severe weather, Temperature drops, clear skies, winds NW, P rises fair but cold weather with passion of cold front
What is occurring in the low pressure cyclone in Figure 19.12?
1) A to E: A is from the south; moving SW but definitely more southerly; will turn NW

2) Winds come from the East and SE; pressure drop b/c low pressure center is coming through

3) High to low clouds, ppt gentle, warm front masses, winds S/Sw, clear skies, then Cb, severe weather T drops, clear skies, winds NW
What occurs north of low pressure center?
1) Winds from east, temperature drops, overcast, progression of clouds, Ci--> Cs--> Ns--> ppt, snow (?)

2) winds NE, N, NW

3) As clouds, P rises, clearing skies, Temperature remains cold
What are lingering cyclones along the New England states
Nor' Easter
the Nor' Easter affected whose weather pattern the most?
US
What are considered severe weather?
Thunderstorms, tornados, and hurricanes
What storm generates lighting and thunder?
Thunderstorm
What weather conditions would one experience in a thunderstorm?
1) Cumulonimbus clouds
2) heavy rain
3) lighting
4) occasion hail
What are the requirements for a Thunderstorm to occur
1) cumulonimbus clouds
2) atmospheric instability needed
How do thunderstorms form?
Warm humid air raises in an unstable environment
What severe weather pattern has an uplift of warm moist air, dew point cases cumulus clouds, and a downdraft of cold air
Thunderstorms
stages of development of thunderstorms?
1) warm moist air rises
2) up draft and down draft
3) rain falls dissipates and rain will cool signing end of storm
In thunderstorms, what is the downdraft of cold air causes by?
expansion and altitude
Which severe weather pattern occurs ahead of cold front and moves in a North East direction?
Tornados
What is a local storm of short duration?
Tornado
What are the conditions of tornados
1) occur along a cold front
2) during spring
3) associated with huge thunderstorms or supercells
Hurricanes have what kind of feedback system?
Positive feedback system
In hurricanes, why does condensation raise temperature?
latent heat
In terms of Hurricanes, what occurs in SE Asian countries; Type of hurricane that causes a lot of damage
Typhoons
What are some examples of Hurricanes?
1) Hurricane Isabel
2) Katrina= damage with the Gulf
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