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142 Cards in this Set

  • Front
  • Back
What is an air mass?
an extremely large body of air whose properties of temperature and humidity are fairly similar in any horizontal direction at any given altitude.
What air masses affect North America?
Continental Polar, Continental Arctic, Maritime Polar, Maritime Tropical, Continental Tropical.
Continental Polar and Continental Arctic
-bitterly cold weather in winter
-invades Southern Canada and US in winter.
-originate over the ice- and snow-covered regions of northern Canada and Alaska
-quite dry
-specific humidities less than 0.3 gram per kilogram
-usually brings relief from heat in summer
Maritime Polar
-originates over Asia and frozen polar regions
-warm and moisture filled air becomes cool, moist, and unstable
Maritime Tropical
-originates from the subtropical east Pacific Ocean
-warm and humid
Continental Tropical
-hot and dry
-originate in northern Mexico and the adjacent southwestern US
What is a front?
When two dissimilar air masses meet, they form a front
A transition zone between two dissimilar air masses
What are the different types of fronts?
warm front, cold front, occluded front, stationary front
Warm Front
a front that moves in such a way that warm air replaces cold air.
As cold air retreats, warm air also glides over cold air forming a ______ _______
gentle slope
gliding (rising) of warm air over cold air, called _____ _____, produces _____. It also creates temperature inversion called _______ ______
over running, clouds, frontal inversion
Warm air that seperates the two air masses has an average slop of _______
precipitation falls ___________ of the front's surface boundary
in advance
precipitation from _______ clouds; light showers that last for _________ _______
nimbostratus, several hours
warm front moves _______
mostly not associated with:
tornadoes, hail, and lightning
Cold Front
a transition sone where a cold air mass advances and replaces a warm air mass
as warm air retreats, it is also forced to rise, forming a _______ ________
steeper slope
a cold front has an average slope of about ____
this favors the development of ________ clouds
precipitation is _____, lasts for a _____ period
heavy, short
precipitation occurs where the front touches the _____
_____ moves faster than _______
cold front, warm front
cold front may produce:
tornadoes, hail, thunder, lightning
occassionally, ahead of a fast-moving cold front, a line of active showers and thunderstorms called _________ decelop-producing strong gusty winds
"squall line"
Occluded Fronts
forms when faster-moving cold front overtakes a warm front
two types of occluded fronts
warm-type and cold-type
when the air behind the front is _____ than the air ahead of it, it is called a cold-type OC
Stationary Front
develops when the surface position of a front does not move.
winds blow almost ________ and from _______ directions on each side of the front
parallel, opposite
what are middle latitude cyclones?
cyclonic storms in middle and higher latitudes
they are sometimes called:
wave cyclones, extratropical cyclones
they develop in _____
what are the stages?
before storm (cyclogenesis or frontogenesis), early stage, mature stage (open stage), occluded stage, dissipation stage (dissolving stage)
before storm (cyclogenesis or frontogenesis) begins at the ______ ______
stationary front
before storm- wind blows almost _____ and from _____ directions on each side of the front
parallel, opposite
Early Stage- stationary front becomes _______
Early Stage- develops a wave called _____ ____ or ____ ____
frontal wave, incipient cyclone
early stage- region of _____ pressure is at the juncion of the two fronts
Mature stage (open stage)- frontal wave _______
mature stage- develops into a _______ cyclone or ____ _____
mature, open wave
mature stage- mature cyclone can be _____ miles or moer in diameter
mature stage- the region between the cold and warm fronts is called the ____ ____
warm sector
occluded stage- faster moving ____ front overtakes the _____ front
cold, warm
occluded stage - ___ air is lifted up from the surface
occluded stage- the ___ pressure center shifts
Dissipation stage or dissolving stage- ______ eliminates surface warm air that provides energy for the cyclone
dissolving stage- the cyclone ___ and ____
weakens and dissipates
dissolving stage - lifespan of a mid latitude cyclone ranges from ______ days
what is a tropical cyclone?
an intense storm of tropical origin
types of tropical cyclones
hurricanes, typhoon, cyclone, baguios
where do these cyclones form?
hurricane- in US (N Amer)
typhoon - western pacific
cyclone- india, east africa, northern australia
baguios- philippine islands
a hurricane develops between ____ and ____ degrees of latitude
5, 20
a hurricane develops over _____ _____
tropical oceans
hurricanes have surface water temps of _____ degrees or greater
hurricanes will not form at the equator where ____ ____ is zero
coriolis force
hurricanes generally move ____ward with ___ ____
west, trade winds
hurricanes have isobars that are more _____, ____ and the ___ ____ is much steeper
circular, compact, pressure gradient
hurricanes derive their energy from the _____ _____ and _____ _____ of condensation released from the towering clouds
warm waters, latent heat
hurricane winds are strongest near the _______
hurricanes usually develop an _____ where the air is _____
eye, sinking
_______ begins with convergence of surface winds
convergence develops a weak trouph of low pressuer called ______ _____, or ______ _______
easterly wave, tropical wave
on the eastern side of the axis, where surface winds converge, rising air generates _______ and _______
showers and thunderstorms
on its western side, where winds diverse, sinking air produces _______ _______
fair weather
hurrican stages of development
tropical disturbance, tropical depression, tropical storm, hurricane.
tropical disturbance
an organized mass of thunderstorms with a slight cuclonic wind circulation of less than 30 mph
tropical depression
a mass of thunderstorms and clouds generally with a cyclonic wind circulation between 30 and 39 mph
tropical storm
organized thunderstorms with a cyclonic wind circulation between 39 and 73 mph
a severe tropical cyclone having winds in excess of 74 mph
the structure of a hurricane consists of:
the eye, and the eye wall
The eye occurs at the ____ of the storm
the eye may exceed _____ miles in diameter
the eye has ____ sky or ____ clouds
clear, broken
the eye has ___ or ____ winds
calm or light
______ pressure is in the eye, about _____ mb with most sorms
lowest, 965
____ air aloft _____ into the eye, warming adiablatically
dry, descends
the eye wall is a ___ of intense _____
ring, thunderstorms
the eye wall ____ around the eye at the ____ speed
rotates, highest
the eye wall has ____ winds
winds in the eye wall ______ as they wirl around the eye
_____ ____ in the eye wall may read _____ to ______ miles from the surface
towering clouds, 6-9
thunderstorms are:
storms containing lightning and thunder
and estimated of ______ thunderstorms develop each day throughout the world. That's over ____ million annually
40,000, 14 million
the majority of thunderstorms develop in _______ regions
in N. Amer., the majority of thunderstorms develop in ______ US
what are the two types of thunderstorms
air-mass thunderstorms and severe thunderstorms
air mass thunderstorms are ____ thunderstorms that form by _______
ordinary, convection
air mass thunderstorms are ______ thunderstorms that form in _____ in ______ latitudes
scattered, summer, middle
air mass thunderstorms form all year round in the ______
air mass thunderstorms are _____ ______ and rarely produce ____ ___ or ____ ___
short lived, strong winds, large hail
air mass thunderstorms develop in stages:
cumulus stage, mature stage, dissipating stage
in the cumulus stage of air mass thunderstorms the cloud is dominated by ______ and soon the could develops into a ______ _____
updrafts, cumulus congestus
in the cumulus stage of air mass thunderstorms there is no _____, ______ or ______
rain, lightening, thunder
in the cumulus stage of air mass thunderstorms, above _____ level, cloud particles ______ _____ and ____ and begin to fall
freexing, grow larger, heavier
in the mature stage of air mass thunderstorms, a ______ _____ cloud develops and ____ and ____ exist side by side
towering, intense, updrafts, downdrafts
in the mature stage of air mass thunderstorms there is ____ rainfall and occassionally small _____
heavy, hail
in the mature stage of air mass thunderstorms ______ are accellerated by the process called ______
downdrafts, entrainment
in the mature stage of air mass thunderstorms ___ air from around the cloud is drawn into the cloud and mixes with saturated cloudy air. This ____ the air and becomes ____
drier, chills, heavier
in the dissipating stage of air mass thunderstorms, updrafts _____, the cloud is dominated by _______, and there are light ____
weaken, downdrafts, showers
severe thunderstorms are capable of producing:
large hail stones larger than .75 inches in diameter, strong gusy surface winds over 58 mph, and tornadoes.
severe thunderstorms are usually assiciated with _____ Fronts and _____ cyclones
cold, tropical
downdrafts and updrafts in severe thunderstorms reinforce one another and ____ the storm
reinforcement in severe thunderstorms requires suitable conditions over an area from ____ to ____ km across. this area size is referred to as _____
10 to 1000, mesoscale
this large area in a severe thunderstorm causes severe storms to appear in ___ or ___. Such clusters are called ______ ______ _____
groups or clusters, mesoscale convective systems (MCSs)
MCS's are also ____ ____
multicell thunderstorms
two basic types of multicell storms are:
mesoscale convective complex or MCC, and squall line thunderstorms
Mesoscale convective compex storms are ______ single-cell thunderstorms with a ___ appearance on an ____ satalite image.
muliple, circular, infared
Mesoscale convective compex storms are ______ lived storms that last for more than ____ hours and cover a ____ area
long, 6, wide
squall line thunderstorms are ____ storm cells arranged in a _____.
intense, line
squall line thunderstorms form ahead of a ____ front.
supercell thunderstorms are enourmous ____ _____ storms.
single cell
supercell thunderstorms ______ and produce very damaging ______.
rotate, tornadoes
updrafts and downdrafts in supercell thunderstorms are ______.
In supercell thunderstorms, cold air of downdrafts forms the ____ ____ and produce extreme downdrafts called _______
gust front, downbursts
in supercell thunderstorms, there are strong, localized downdrafts less than ____ km in diameter beneath a storm called _______
4, microburst
a supercell thunderstorm more than 4 km is a _______
tornadoes are _____ of thunderstorms. The majority develop from ______ storms.
offspring, supercell
tornadoes have a diameter between _____ and ______ ft and have an average path of __ miles
300, 8000, 4
The US experiences ___ tornadoes than any other coutry (over ____ annually)
more, 1000
Tornadoes have occured in _____ state. The greatest # occur in the ____ ___ or ___ ___ of the central pains.
every, tornado belt, tornado ally
about ___% of tornadoes develp from ____ to ______ in teh US. ___ has the greatest # of tornadoes.
75, march, july, may
the ____ ___ region is the most susceptible to tornadoes
central plains
What conditions lead to the formation of a tornado?
rotating updrafts with a severe thunderstorm called mesocyle and a funnel cloud
in the first mesocyclone stage, it rotates ____, ____, and _____
slowly, wider, and shorter
in the second stage of a mesocyclone, it stretches ______, _______, and rotates _____
vertically, narrows, faster
in teh thrid stage of a mesocyclone, it develops a ____ ___ at the cloud base called a ____ ___
dark cloud, wall cloud
in the fourth stage of a mesocyclone, the wall could ____ at the base of the cloud
a ____ ___ develops from the protruding wall cloud
funnel cloud
a ___ ___ is issued when a funnel cloud is spotted
tornado warning
fujita scale for damaging wind
about _____ of tornadoes in US fall into F0 or F1 category
when a tornado occurs over water surface, a ____ ____ forms
water sprout
tornado alley includes 9 states:
texas, oklahoma, kansas, arkansas, missouri, nebraska, iowa, alabama, mississippi
electrical discharge produced by mature storms
lightning may take place withing a ____, from one ___ to another, from cloud to surrounding ____, from cloud to _____
cloud, cloud, air, ground
lightning stoke heats the air to very high temps and the extreme heating causes air to expand ____, causing _____
explosively, thunder
cloud to ground lightening to occur, air between cloud ____ and ____ has to be _____ first
base, ground, ionized
cloud to ground lightening to occure, localized electricity field at cloud base ____ ____ in the air, ionizing teh air. this prepares a conductive path called _____ or ___ ____
frees electrons, leader, step leader
step leader is an initial discharge of _____ that proceeds intermittently in a series of steps. This is not visable to the human eye.
return stroke:
the luminous lightening stroke that propells upward from the earth to the base of the cloud
dart leader
re-ionizes the conductive path. it is continuous and less brached than a step leader