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142 Cards in this Set
- Front
- Back
What is an air mass?
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an extremely large body of air whose properties of temperature and humidity are fairly similar in any horizontal direction at any given altitude.
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What air masses affect North America?
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Continental Polar, Continental Arctic, Maritime Polar, Maritime Tropical, Continental Tropical.
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Continental Polar and Continental Arctic
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-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 |
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Maritime Polar
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-originates over Asia and frozen polar regions
-warm and moisture filled air becomes cool, moist, and unstable |
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Maritime Tropical
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-originates from the subtropical east Pacific Ocean
-warm and humid |
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Continental Tropical
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-hot and dry
-originate in northern Mexico and the adjacent southwestern US |
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What is a front?
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When two dissimilar air masses meet, they form a front
A transition zone between two dissimilar air masses |
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What are the different types of fronts?
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warm front, cold front, occluded front, stationary front
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Warm Front
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a front that moves in such a way that warm air replaces cold air.
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As cold air retreats, warm air also glides over cold air forming a ______ _______
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gentle slope
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gliding (rising) of warm air over cold air, called _____ _____, produces _____. It also creates temperature inversion called _______ ______
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over running, clouds, frontal inversion
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Warm air that seperates the two air masses has an average slop of _______
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1:300
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precipitation falls ___________ of the front's surface boundary
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in advance
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precipitation from _______ clouds; light showers that last for _________ _______
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nimbostratus, several hours
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warm front moves _______
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slowly
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mostly not associated with:
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tornadoes, hail, and lightning
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Cold Front
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a transition sone where a cold air mass advances and replaces a warm air mass
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as warm air retreats, it is also forced to rise, forming a _______ ________
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steeper slope
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a cold front has an average slope of about ____
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1:50
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this favors the development of ________ clouds
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thunder-cumulunimbos
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precipitation is _____, lasts for a _____ period
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heavy, short
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precipitation occurs where the front touches the _____
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surface
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_____ moves faster than _______
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cold front, warm front
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cold front may produce:
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tornadoes, hail, thunder, lightning
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occassionally, ahead of a fast-moving cold front, a line of active showers and thunderstorms called _________ decelop-producing strong gusty winds
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"squall line"
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Occluded Fronts
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forms when faster-moving cold front overtakes a warm front
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two types of occluded fronts
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warm-type and cold-type
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when the air behind the front is _____ than the air ahead of it, it is called a cold-type OC
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colder
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Stationary Front
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develops when the surface position of a front does not move.
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winds blow almost ________ and from _______ directions on each side of the front
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parallel, opposite
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what are middle latitude cyclones?
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cyclonic storms in middle and higher latitudes
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they are sometimes called:
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wave cyclones, extratropical cyclones
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they develop in _____
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stages
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what are the stages?
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before storm (cyclogenesis or frontogenesis), early stage, mature stage (open stage), occluded stage, dissipation stage (dissolving stage)
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before storm (cyclogenesis or frontogenesis) begins at the ______ ______
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stationary front
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before storm- wind blows almost _____ and from _____ directions on each side of the front
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parallel, opposite
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Early Stage- stationary front becomes _______
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unstable
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Early Stage- develops a wave called _____ ____ or ____ ____
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frontal wave, incipient cyclone
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early stage- region of _____ pressure is at the juncion of the two fronts
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lowest
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Mature stage (open stage)- frontal wave _______
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intensifies
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mature stage- develops into a _______ cyclone or ____ _____
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mature, open wave
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mature stage- mature cyclone can be _____ miles or moer in diameter
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500
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mature stage- the region between the cold and warm fronts is called the ____ ____
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warm sector
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occluded stage- faster moving ____ front overtakes the _____ front
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cold, warm
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occluded stage - ___ air is lifted up from the surface
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warm
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occluded stage- the ___ pressure center shifts
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low
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Dissipation stage or dissolving stage- ______ eliminates surface warm air that provides energy for the cyclone
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occlusion
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dissolving stage- the cyclone ___ and ____
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weakens and dissipates
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dissolving stage - lifespan of a mid latitude cyclone ranges from ______ days
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1-5
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what is a tropical cyclone?
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an intense storm of tropical origin
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types of tropical cyclones
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hurricanes, typhoon, cyclone, baguios
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where do these cyclones form?
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hurricane- in US (N Amer)
typhoon - western pacific cyclone- india, east africa, northern australia baguios- philippine islands |
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a hurricane develops between ____ and ____ degrees of latitude
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5, 20
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a hurricane develops over _____ _____
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tropical oceans
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hurricanes have surface water temps of _____ degrees or greater
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80
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hurricanes will not form at the equator where ____ ____ is zero
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coriolis force
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hurricanes generally move ____ward with ___ ____
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west, trade winds
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hurricanes have isobars that are more _____, ____ and the ___ ____ is much steeper
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circular, compact, pressure gradient
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hurricanes derive their energy from the _____ _____ and _____ _____ of condensation released from the towering clouds
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warm waters, latent heat
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hurricane winds are strongest near the _______
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surface
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hurricanes usually develop an _____ where the air is _____
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eye, sinking
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_______ begins with convergence of surface winds
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cyclogenesis
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convergence develops a weak trouph of low pressuer called ______ _____, or ______ _______
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easterly wave, tropical wave
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on the eastern side of the axis, where surface winds converge, rising air generates _______ and _______
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showers and thunderstorms
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on its western side, where winds diverse, sinking air produces _______ _______
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fair weather
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hurrican stages of development
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tropical disturbance, tropical depression, tropical storm, hurricane.
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tropical disturbance
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an organized mass of thunderstorms with a slight cuclonic wind circulation of less than 30 mph
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tropical depression
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a mass of thunderstorms and clouds generally with a cyclonic wind circulation between 30 and 39 mph
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tropical storm
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organized thunderstorms with a cyclonic wind circulation between 39 and 73 mph
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hurricane
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a severe tropical cyclone having winds in excess of 74 mph
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the structure of a hurricane consists of:
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the eye, and the eye wall
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The eye occurs at the ____ of the storm
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center
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the eye may exceed _____ miles in diameter
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20
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the eye has ____ sky or ____ clouds
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clear, broken
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the eye has ___ or ____ winds
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calm or light
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______ pressure is in the eye, about _____ mb with most sorms
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lowest, 965
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____ air aloft _____ into the eye, warming adiablatically
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dry, descends
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the eye wall is a ___ of intense _____
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ring, thunderstorms
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the eye wall ____ around the eye at the ____ speed
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rotates, highest
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the eye wall has ____ winds
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strongest
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winds in the eye wall ______ as they wirl around the eye
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ascend
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_____ ____ in the eye wall may read _____ to ______ miles from the surface
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towering clouds, 6-9
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thunderstorms are:
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storms containing lightning and thunder
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and estimated of ______ thunderstorms develop each day throughout the world. That's over ____ million annually
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40,000, 14 million
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the majority of thunderstorms develop in _______ regions
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tropical
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in N. Amer., the majority of thunderstorms develop in ______ US
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southeast
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what are the two types of thunderstorms
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air-mass thunderstorms and severe thunderstorms
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air mass thunderstorms are ____ thunderstorms that form by _______
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ordinary, convection
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air mass thunderstorms are ______ thunderstorms that form in _____ in ______ latitudes
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scattered, summer, middle
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air mass thunderstorms form all year round in the ______
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tropics
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air mass thunderstorms are _____ ______ and rarely produce ____ ___ or ____ ___
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short lived, strong winds, large hail
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air mass thunderstorms develop in stages:
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cumulus stage, mature stage, dissipating stage
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in the cumulus stage of air mass thunderstorms the cloud is dominated by ______ and soon the could develops into a ______ _____
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updrafts, cumulus congestus
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in the cumulus stage of air mass thunderstorms there is no _____, ______ or ______
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rain, lightening, thunder
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in the cumulus stage of air mass thunderstorms, above _____ level, cloud particles ______ _____ and ____ and begin to fall
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freexing, grow larger, heavier
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in the mature stage of air mass thunderstorms, a ______ _____ cloud develops and ____ and ____ exist side by side
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towering, intense, updrafts, downdrafts
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in the mature stage of air mass thunderstorms there is ____ rainfall and occassionally small _____
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heavy, hail
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in the mature stage of air mass thunderstorms ______ are accellerated by the process called ______
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downdrafts, entrainment
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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 ____
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drier, chills, heavier
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in the dissipating stage of air mass thunderstorms, updrafts _____, the cloud is dominated by _______, and there are light ____
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weaken, downdrafts, showers
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severe thunderstorms are capable of producing:
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large hail stones larger than .75 inches in diameter, strong gusy surface winds over 58 mph, and tornadoes.
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severe thunderstorms are usually assiciated with _____ Fronts and _____ cyclones
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cold, tropical
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downdrafts and updrafts in severe thunderstorms reinforce one another and ____ the storm
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intensify
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reinforcement in severe thunderstorms requires suitable conditions over an area from ____ to ____ km across. this area size is referred to as _____
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10 to 1000, mesoscale
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this large area in a severe thunderstorm causes severe storms to appear in ___ or ___. Such clusters are called ______ ______ _____
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groups or clusters, mesoscale convective systems (MCSs)
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MCS's are also ____ ____
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multicell thunderstorms
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two basic types of multicell storms are:
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mesoscale convective complex or MCC, and squall line thunderstorms
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Mesoscale convective compex storms are ______ single-cell thunderstorms with a ___ appearance on an ____ satalite image.
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muliple, circular, infared
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Mesoscale convective compex storms are ______ lived storms that last for more than ____ hours and cover a ____ area
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long, 6, wide
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squall line thunderstorms are ____ storm cells arranged in a _____.
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intense, line
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squall line thunderstorms form ahead of a ____ front.
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cold
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supercell thunderstorms are enourmous ____ _____ storms.
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single cell
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supercell thunderstorms ______ and produce very damaging ______.
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rotate, tornadoes
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updrafts and downdrafts in supercell thunderstorms are ______.
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tilted
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In supercell thunderstorms, cold air of downdrafts forms the ____ ____ and produce extreme downdrafts called _______
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gust front, downbursts
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in supercell thunderstorms, there are strong, localized downdrafts less than ____ km in diameter beneath a storm called _______
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4, microburst
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a supercell thunderstorm more than 4 km is a _______
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macroburst
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tornadoes are _____ of thunderstorms. The majority develop from ______ storms.
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offspring, supercell
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tornadoes have a diameter between _____ and ______ ft and have an average path of __ miles
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300, 8000, 4
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The US experiences ___ tornadoes than any other coutry (over ____ annually)
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more, 1000
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Tornadoes have occured in _____ state. The greatest # occur in the ____ ___ or ___ ___ of the central pains.
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every, tornado belt, tornado ally
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about ___% of tornadoes develp from ____ to ______ in teh US. ___ has the greatest # of tornadoes.
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75, march, july, may
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the ____ ___ region is the most susceptible to tornadoes
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central plains
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What conditions lead to the formation of a tornado?
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rotating updrafts with a severe thunderstorm called mesocyle and a funnel cloud
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in the first mesocyclone stage, it rotates ____, ____, and _____
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slowly, wider, and shorter
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in the second stage of a mesocyclone, it stretches ______, _______, and rotates _____
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vertically, narrows, faster
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in teh thrid stage of a mesocyclone, it develops a ____ ___ at the cloud base called a ____ ___
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dark cloud, wall cloud
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in the fourth stage of a mesocyclone, the wall could ____ at the base of the cloud
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protrudes
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a ____ ___ develops from the protruding wall cloud
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funnel cloud
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a ___ ___ is issued when a funnel cloud is spotted
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tornado warning
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fujita scale for damaging wind
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F0 AND F1 WEAK
F2 AND F3 STRONG F4 AND F5 VIOLENT |
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about _____ of tornadoes in US fall into F0 or F1 category
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2/3
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when a tornado occurs over water surface, a ____ ____ forms
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water sprout
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tornado alley includes 9 states:
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texas, oklahoma, kansas, arkansas, missouri, nebraska, iowa, alabama, mississippi
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Lightening
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electrical discharge produced by mature storms
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lightning may take place withing a ____, from one ___ to another, from cloud to surrounding ____, from cloud to _____
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cloud, cloud, air, ground
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lightning stoke heats the air to very high temps and the extreme heating causes air to expand ____, causing _____
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explosively, thunder
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cloud to ground lightening to occur, air between cloud ____ and ____ has to be _____ first
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base, ground, ionized
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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 ___ ____
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frees electrons, leader, step leader
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step leader is an initial discharge of _____ that proceeds intermittently in a series of steps. This is not visable to the human eye.
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electrons
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return stroke:
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the luminous lightening stroke that propells upward from the earth to the base of the cloud
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dart leader
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re-ionizes the conductive path. it is continuous and less brached than a step leader
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