Atmosphere Notes Part 3
A. Air Masses
a. Air Masses
i.
Weather patterns result from a ______ of a large body of air.
ii.
Characterized by similar _________ and amounts of _______ at any given altitude.
iii.
Could take several days for an air mass to move across an area = ________ weather
b. Movement of Air Mass
i.
When the air mass moves out of the region it is formed in, it takes the ______ _______ with it.
ii.
The air mass _______ as it moves as well
c. Classifying Air Mass
i.
_____________ - the area that an air mass gets its characteristics properties of
temperature and moisture
1. ______ (P) and __________ (T) - describe ___________
2. __________ (c) and ______________ (m) - where they form and ___________
characteristics
d. Weather in N. America
i.
Majority of weather is influenced by the _____ and _____ air mass
1. Form in _________/northern Canada and _______
ii.
cP (___________________) - uniformly cold and dry in _____ and cool and dry in __________
1. Lake Effect = when the temperature of the lake and the land are extremely different
causing heavy and unstable air, leads to heavy snow (________)
iii.
mT (__________________) - warm, loaded with moisture, usually unstable
1. Responsible for most of the precipitation in the eastern US
2. In summers brings high temps and humidity
iv.
mP (_________________) - originate off the coast of eastern Canada
1. Can bring with it heavy snow/rain (from Siberia to western coast of US)
2. Nor’easter = snow and cold temperatures as low pressure center passes, going counter
clockwise
v.
cT (_________________) - least influence on the weather in NA
1. Hot dry air masses begin the southwestern US and Mexico during summer
2. Cause extreme hot, drought like conditions in the Great Plains during the summer
3. Indian Summer - mild weather in the Great Lake region (unseasonably warm and mild)
B. Fronts
a. Formation of Fronts
i.
When _____ air masses meet form a _____, a ____ that separates two air masses
ii.
Fronts are ________, associated with _____, usually act as a ____ that travels with an air mass,
classified according to the ______ of the advancing front.
b. Warm Front
i.
When warm air moves into an area formerly covered by cold air
1. _______ slope as warm air rises, produces _____, leads to ______
2. ______ moving front
3. Light to moderate precipitation
ii.
Shown by _____ lines and semicircles on a weather map that point towards the _______ air.
c. Cold Front
i.
Forms when cold dense air moves into a region occupied by warmer air
1. Becomes a ______ slope, advance ____
2. _____ weather (heavy downpour, gusty winds)
3. Behind a _____ front weather is dominated by a cold air mass
ii.
Shown by a ______ line with triangles that point towards the _____ air mass
d. Stationary Front
i.
When the surface position of the front does not move
1. The flow of air is _____ toward the cold air mass or the warm air mass
2. ______ to _____ precipitation can occur
ii.
Shown by ____ triangles on one side and _____ semicircles on the other side of the front line
e. Occluded Front
i.
An active cold front overtakes a warm front
1. The cold air mass _____ the warm front ______
2. ______ weather (due to warm air going up)
3. Can make its own light precipitation
ii.
Shown on a weather map by _____ triangles and red _______ on the same side of the front line.
f. Middle Latitude Cyclones
i.
Main weather producers in the country (North America)
1. Centers of _______ pressure that generally travel from _____ to _____, cause stormy
weather
2. Move in a _______ direction (towards the center of the low)
3. Must have a _____ front - lifting cause the formation of ______ and abundant ______
ii.
Low pressure system shown on a map by a ______
g. How do they form?
i.
_________ of a front (two air masses with different temps move in _____ directions)
ii.
Front takes on a ___ shape
iii.
Warm air moves towards Earth’s ______, cold air moves towards the _____
iv.
The change in airflow near the surface is associated with a change in pressure (resulting in a
counterclockwise direction)
v.
_______ front forms - storm gets stronger
vi.
When all the warm air is gone the _____ of the air and the _____ slows the airflow and it “dies”
h. The Role of Airflow Aloft
i.
More often than not, air high up in the atmosphere fuels a _______ latitude cyclone.
ii.
Usually can find _____ and ______ next to each other.
C. Severe Storms
a. Thunderstorms
i.
_________ movement of warm ________ air can lead to a thunderstorm
ii.
iii.
iv.
Generates ______ and ______, produce gusty winds, heavy rain, and sometimes hail
Could be a single _________ cloud or a large stretch along a ______ front.
Greatest number of thunderstorms occur in the ______ - due to the warm, moisture rich, and
unstable air
v.
Development - when warm, humid air rises in an unstable environment (lifespan about 2hrs)
1. Strong ________ movements of warm moist air
2. ______ stage - amount and size of ______ due to the updraft is too large to be supported
(most active stage)
3. Dissipating Stage - when the _____ dominant, cooling effect of the falling precipitation
causes the storm to die.
b. Tornadoes
i.
__________ windstorms that take the form of a rotation of air called a _______ extends
downwards
ii.
Tornado season - _______ through _____ (December and January less frequent)
iii.
Form with _______ thunderstorms
iv.
__________ - important to form tornado, a vertical cylinder of rotated air that develops in the
updraft
c. Tornado Intensity and Safety
i.
Wind speeds is measured by the _______ scale - winds cannot be measured directly so
determined by the amount of damage done
ii.
Tornado _________ - the possibility of a tornado (favorable conditions)
iii.
Tornado _________ - tornado has actually been seen in the area or on the weather radar
d. Hurricanes/Typhoons/Cyclones
i.
Tropical cyclones that produce winds of at least _______
ii.
Most powerful storm on Earth
iii.
Can bring to shore strong winds, storm surge, and flooding
iv.
A higher threat now that more people live and work near the coastline
e. Development of a Hurricane
i.
A _____ engine that is fueled by the energy given off when huge quantities of water vapor
condense
ii.
Develop most often in the ____ summer when water temps are _____ enough to provide heat and
________ to the air.
iii.
Tropical disturbance to a category 5 hurricane
1. Eye Wall - is formed and usually helps to sustain the hurricane (strongest wind gust are
here)
f. Hurricane Safety
i.
Intensity measured by the ______ scale
ii.
Storm Surge - water that precedes the hurricane and sweeps onto the shore/land
iii.
Hurricanes weaken as they move over _____ water (lack of adequate heat and moisture) or land
(due to friction and lack of moisture)
D. Climate Change
a. Climate is always changing (short - term or long - term)
b. Natural Process that change climate
i.
Volcanic Eruption
ii.
Ocean Circulation
iii.
Solar Activity
iv.
Earth Motions
c. Volcanic Eruptions
i.
Emits large amounts of ________ and ______ into the atmosphere
ii.
Aerosols in the air _________ solar radiation reflected back into space - ________ the atmosphere
temperatures (Volcanic winter)
d. Ocean Circulations
i.
___________ the change in ocean circulation
ii.
_____ term climate fluctuations
iii.
Ex.) An area that usually has a lot of rain could experience a drought during an El Nino
e. Solar Activity
i.
Changes in the ______ of the solar activity
ii.
__________ = warm periods in Europe and North American
iii.
Short term effects
iv.
No long term variations due to solar activity exist (yet)
f. Earth Motions
i.
Most are _______ term changes
ii.
________ plate movement - change in position of land and oceans
iii.
Shape of the _______ and ______ of the Earth on the axis
1. Smaller the tilt the smaller the temperature difference between summer and winter
g. Human Impact on Climate Change
i.
Greenhouse Effect - a ______ warming of both Earth’s lower atmosphere and surface.
1. Major gases involved - ____________ and ________
2. Makes life possible on Earth
3. Human impact has increased ________ levels in the ______ (burning of ________ and
________ of forest)
ii.
Global Warming - a result of the ______ in _______ and other gases --- global temperatures have
_______
1. Sea level rising, flooding, heat waves, droughts, more water vapor in the air, temperature
increases across the globe.