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Weather
factors of weather
35
Geography
11/02/2011

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Term
Weather
Definition
local temperature and precipitation on a daily basis
climate: long term temperature and precipitation based on seasons
Term
earth sun relations
Definition
earth rotates on its axis every 24 hours
earth revolves around sun every 365.25 days
earth's axis- titled 23.5 degrees off the perpendicular to the plane of the ecliptic
-tile fo teh earth causes seasons.
Term
Atmosperic heating and cooling
Definition
insolation- incoming solar radiation
-indirectly heats the surface of the earth
-most intense and long duration INSOLATION come from vertical rays of earth
-earth absorbs and reflects some short-wave (light)energy
-absorbed engery is re-radiated as long wave energy of heat
Term
Soalr radiation
Definition
earth absorbs some light energy and relfects some light energy. The absorbed energy is then re-radiated as long wave or heat energy taht heats the atmosphere from the bottom up.
Term
atmosphere heating and cooling 2
Definition
changes in sun angle affect insolation in terms of duration and intensity
-at low latitudes angle is 90 degrees meanin glong duration, high intensiy insolation thus making it hot
-at mid latitudes angle is shallower meaning energy is dissipated over a larger area making in cooler
-at high latitudes angle is really shallow dissipating energy over a lot of area making it cold
Term
atmospheric heating and cooling 3
Definition
altitude cools off air as it rises- standard atmospheric lapse rate is 3.5 degrees/f per 1000 feet of altitude
-normally air is unstable with cold/sinking air on top and warm/rising air on bottom
-a temp inversion occurs when warm air is trapped between cold air and nothing moves (this can be dangerous)
Term
nature of wind
Definition
Pressure gradient force- wind flows from high pressure to low presure (flows perpendicular to isobars)
-Coriolis affect- apparent deflection of wind due to earth's rotation makes wind bend to right in NHemisphere and left in Shemisphere (parallel to isobars)
friction zone- below 5000 feet friction with ground causes wind to flow diagonal to isobars.
Term
cyclones
Definition
low pressure center
counerclockiwisde in Nhemisphere (opposite in southen)
-at ground level air is converging
-air rises in low pressure center
-an altitude air diverges outward
Term
anticyclone
Definition
air is subsiding (droping towards ground)
-at ground level air is diverging
-an altitude air is coverging
Term
global atmospheric circulation
Definition
-Earth has 7 semi-permanent pressure features
-Isolation causes a low pressure belt
-dynamically induced sub tropical high occur
-sub polar lows occur about 60 degrees N and S latitude
-Polar highs occur at the poles
-trade winds flow between these feature
Term
humidity
Definition
absolute humidity - weight of water vapor/volume of air in grams per square meter
relative humidity- amount of water vapor compared to capacity as a eprcentage
Term
Condensation
Definition
-condensation occurs at 100% relative humidy (clouds)
-Precipitation at 100%+ relative humidity (with condensation nuclei)
Term
adiabatic warming
Definition
as a parcel of air rises, it adiabatically COOLS, as it adiabaticallly cools its capacity to hold moisture DECREASES, as its capacity to hold moisture decreases, its relative humidity INCREASES. At 100% clouds form and at 100%+ (with condensation nuclei) percipitation occurs.
Term
adiabatic cooling
Definition
as a parcel of air SINKS, it adiabatically warms its capacity to hold moisture increases, as its capacity to hold moisture increases, its relative humidity decreases. As relative humidity decreases there is no cloud formation or precipitation.
Term
atmospheric lifting
Definition
3 mechanisms
-frontal- two unlike airmases meet
-orographic- moutains cause air to rise
-convective/convergent- hot ground heats air and air converges from high to low
Term
cumuliform
Definition
high vertical, low horizontal extent
cumuloimbus
Term
stratiform
Definition
(flat and sheet-like)
-low vertical, large horizontal extent
-nimbostratus
Term
cirriform
Definition
ice crystals in upper atmosphere
-do not produce precipitation
Term
precipitation
Definition
four types
rain- liquid water
snow- vapor to solid crystal
hail- frozen rain
sleet- chunks of ice from recirculation by updraft
Term
airmasses
Definition
large (sub-continental in size) 1000+ miles across
-horizontally uniform to temperature and moisture
-appear and travel as a recognizable entity
Term
airmasses
Definition
large (sub-continental in size) 1000+ miles across
-horizontally uniform to temperature and moisture
-appear and travel as a recognizable entity
Term
Airmass source regions
Definition
-c Continental (dry)
-m Maritime (wet)
-t Ttropical (warm)
-a Artic (cold)
-e equatorial (hot)
-north american airmasses cP, cT,cP. mT
Term
fronts
Definition
when unlike airmasses meet they do not easily mix but form fronts
characteristics
-transitonal boundary miles wide
-lean with height
-warm air always rises over cold air
Term
fronts
Definition
when unlike airmasses meet they do not easily mix but form fronts
characteristics
-transitonal boundary miles wide
-lean with height
-warm air always rises over cold air
Term
warm fronts
Definition
warm air is displacing cold air
-warm air gently rises up over cold air
characteristics
-shallow slope 1:200
-stratiform clouds (possible cirrus clouds)
-low intensity, long duration precipitation
Term
cold front
Definition
-cold air is displacing warm air
-cold air forces warm air to rise vionetly and rapidy
characteristics
-steep slope 1:40
-cumuliform clouds
-high intensity, short duration precipitation
Term
stationary frotns
Definition
-neither air mass displaces the other
-weather is unpredictable but can produce low intensity, long duration precipitation due to gently rising air
Term
extra tropical cyclones
Definition
-sub continental in size (1000 miles across)
-centered on surface low of 990-1000 mb
-characteristic warm and cold front extends from low pressure center
-cold front moves faster than warm front and chases it
-cold front overtakes warm front, lifts warm air out of contact with ground causing an occluded front.
Term
ETC movement
Definition
-four axis of movement
-air converges into the low pressure center
-warm front rotates counter-clockwise
-cold front rotates counter-clockwise
-whole ETC moves from west to east with the belt of the westerlies
Term
Occluded Front
Definition
as the cold front overtakes the warm front, the warm air is lifted out of contact with the ground causing an occluded front
Term
occluded front characeristics
Definition
-warm air is lifted out of contact with ground
-both cumuliform and stratiform clouds develop
-long duration and high intensity
-occulsion usually occurs over Eastern US and Canada
-full occulusion is the death of the cyclone since there is no more rising air
Term
life cycle of extra tropical cyclone
Definition
cyclongenisis- borth of the ETC when warm and cold airmasses meet and condition in upper atmospher cause ETC to start spinning and move out in belt of westerly winds
-maturity- ETC has well developed warm and cold fronts
-partial occlusion- cold frotn partialy overtakes warm front from center out
-full occlusion
cold front completely lifts warm air out of contact with th ground depriving the cyclone of it's energy and killing it
Term
extra tropical anticyclones
Definition
ETAC referred to a high because it is based on a high pressure center
-migratory high pressure cell typically larger than an etc
-etc and etacs alternate as they move with the westerlies
-high presure does nto produce precp
Term
climate controls
Definition
latitude-insolation, pressure and winds
land/water contrasts- humid versus continental, monsoons
topographic barriers
ocean currents
altitude
Term
koeppen
Definition
based his system on temp and percep
used vegestation as a proxy indicator evident in the landscape
capital letters for macro-regions with small letter to delinate sub climates