source regions
areas of the globe where air masses form
How are air masses classified
temperature and moisture characteristics of their source regions
air masses based on moisture content
Maritime (m)-moist
Continental (c)-dry
air masses based on temperature
tropical (T)-warm
polar (P)-cold
Arctic (A)-extremely cold
movement of an air mass away from its source causes two things
region to which the air mass moces undergoes a major change in temp and humidity
the air mass becomes more moderate
type and properties at source
Continental polar
cold and dry
very stable
minimal cloud cover
type and properties at source
Continental arctic
extremely cold and very dry
extremely stable
minimal cloud cover
type and properties at source
Maritime polar
cold damp and cloudy
somewhat unstable
type and properties at source
Continental tropical
hot and dry
very unstable
type and properties at source
maritime tropical
warm and humid
source regions
high-lat continental interiors
source regions
highest lat of asia, NA, greenland and antarctica
source regions
high-lat oceans
source regions
low-lat deserts
source regions
subtropical oceans
four types of fronts
cold front
occurs when a wedge of cold air advances toward the warm air ahead of it
warm front
represents the boundary of warm air mass moving toward a cold one
light, continuous precipitation
stationary front
similar to cold in structure but has not recently undergone substantial movement
appear at the surface as boundary between two polar air masses, with a colder polar air mass usually advancing on a slightly warmer air mass ahead of it.
cold front closes on a warm front
typical cold front surface slope
about 1:100
surface rises only 1 m for every 100m of horizontail extent
cold-type occlusion location
eastern half of continent
warm-type occlusion location
western half of continent
areas where mT and cT airmasses reside next to each other
strong humidity boundary
temp and dew points prior to and following a dryline
substantail drop in humidity and slight increase in temp
air mass
term for large body of air with similar temp and moisture characteristics
source regions
areas of the globe where air masses form
describe cT air massess
hot and dry
very unstable
describe mP air masses
cold damp and cloudy
somewhat unstable
describe cP air masses
cold and dry
very stable
minimal cloud cover
warm air sliding over a dense cold air mass
the characteristic flow associated with a warm front
statistical properties of the atmosphere
includes measures of average conditions and varability
climatic normal
the average value of some weather variable
such as daily high temperaturem for a recent 30-year period
todays climatic normal period
climate variables
temp and precipitation
net radiation
controlling factors for climate
marine/continental-uneven distribution of land and ocean
earth-sun relationships–position of Earth in orbit influence amount of radiation recieved
latitude–influence sun angle and length of day
aircirculation–flow of air and position of high and low pressure systems
topography–high-elevation locations colder than would be expected solely based on lat
Thornthwaite’s classification system
developed to distinguish climates based on moisture availability
moisture index
thermal efficiency of a location
The Koeppen system
A-E classification system based relationship between Vegetation climate characteristics
based on average monthly precipitation and temp and total annual precipitation of a location to determine the climate zone
The Koeppen system–A
all months have avg temp greater than 18 C
The Koeppen system–B
potential evaporation exceeds precipitation
The Koeppen system–C
Mild Midlatitude
coldest month of the year has an avg temp higher than -3C but below 19C. summers can be hot
The Koeppen system–D
Severe Midlatitude
winters have at leawst occasional snow cover.
coldest month having a mean temp below -3C. summers are typically mild
The Koeppen system–E
all months have mean temp below 10C
A climate
(0-25′ N/S lat)
Af–tropical wet
Aw–tropical wet and dry
Tropical wet–has no dry seasons at all
monsoonal climate–has a short dry season while rest of the year is rainy
Tropical wet and dry–have a distinct dry season, usually coinciding with the seasonal presence of subtropical high pressure of hadley circulation
B climates–
(near 30′ N/S lat)
BWh–subtropical desert
BWk–midlatitude desert
BSh–subtropical steppe
BSk–midlatitude steppe
BWh & BWk
True desert class
subtropical desert
midlatitude desert
BSk & h
midlatitude steppe
subtropical steppe
C climates
20-60′ N/S lat
Cfa, Cfb, Cwa, Cwb–humid subtropical
Csa, Csb–mediterranean
Cfc, Cwc, Csc–marine west coast
D climates
35-60′ N latitude
Dsa, Dsb–Summer dry Warm
Dsc, Dsd– Summer dry Cold
Dwa, Dwb– Winter dry Warm
Dwc, Dwd– Winter dry Cold
Dfa, Dfb– No dry season Warm
Dfc, Dfd–No dry Season Cold
Dfa, Dfb, Dwa, Dwb, Dsa, Dsb
humid continental
Dfc, Dfd, Dwc, Dwd, Dsc, Dsd
E and H climates
EF–Ice cap
Highland (H)
influenced by temp changes with elevation
highland complex characteristics
slope orientation
time of day
direction of airflow
orographic uplift
Category of Koppen climates used for tropical environment
BEst variable for identifying a desert or steppe climate
annual precipitation
Category of Koppen climates that exists almost ecvlusively in the N hemispher
which state are you most likely to find a mediterranean (Csa or Csb) climate
Califoria–marine west coast
a tropical wet and dry climate typically has a ____ winter
data shown in a climograph
illustrates the seasonality of temp and precipitation for climate
associated with tropical wet and dry climates
vegetation consisits mainly of grasses
boundary conditions
a configuration of external factors that influence a system
such as Earth’s atmosphere
forcing agents
external conditions that can drive climate changes
feedback processes
in natural systems the manner in which a change in one var is muted or enhanced by its impact on a another other variable
positive feedback ex
the high albedo of snow amplifies the effect of decreasing incoming solar radiation
negative feedback ex
increasing temp gradient across the mid lat gives rise to neg feedback
proxy indicators
climate change science some indicator of previous conditions used in the absence of direct measurements
former earth climates
defining climate change
change in the statistical properties of atmoshperic variables
inter- and intra-annual variations may obscure changes
methods for determining past climates
ocean deposits
remnant landforms
past vegetation
ice cores
ice-rafted debris
rock material transported by icebergs that is eventually deposited on the ocean floor when the iceberg melts
ice cores
extractions from glaciers used to obtain information about past climates
Climate was ____C warmer than present
earliest known ice age
about 2.8 billion years ago
current ice age began __ million years ago and persists ______
55 mill
last glacial maximum
ice sheet 3500 to 4000 m thick
sea levels 120 m lower than now
2.5 mill years ago
glacial/interglacial cycles
episodic climate changes associated with the advance and retreat of glaciers
last 20,000 years ice age
Younger Dryas
cold period about 13,000 years ago lasting about 1200 years
Little ice age
the last century warming and cooling pattern w/ years
snowball earth
about 700 million years ago
nearly the entire planet might have been ice covered
impacts of warming on temp-related var
fewer days with frost
decrease in number of extreme cold events
snow cover decrease
river and lake icea break-up date earlier, freeze-up date later
decrease in extent of frozen ground
factors involved in climatic change
changes in solar output
changes in sun/earth relationships
changes in land surface
changes in atmospheric composition
factors involved in climatic change:
solar output
0.1-0.2 percent change due to 11-year sunspot cycle
the maunder minimum conincided with little ice age
maunder minimum
a period of Earth’s history between about 1645-1715–charterized by minimal sunspot activity
quasi-biennial oscillation (QBO)
a periodic reversal in the direction of lower stratospheric winds over the tropics occuring on an about 2-year cycle
Milankovitch cycles
variations in earths orbital characteistics having periodicities of tens of thousands of Years and longer
the degree to which an elliptically orbitiing planet orbit departs from a true circle
the degree of tilt of earth’s axis relative to the exlipitc plane
the wobble of earth’s acis that has a periodicity of about 27,000 years.
factors involved in climatic change:
land surface
plate tectonics
landuse changes such as deforestation or desertification
factors involved in climatic change:
atmospheric composition
tropospheric aerosols–reduction in surface heating and short residence times
stratospheric aerosols–reductions in surface heating and longer residence times
cold front passage
dew pt drops with temp
wind directions shifts from s to w or nw
precipiation ahead of front
pressure decrease
begining of a cyclone
severe thunderstorms
wind exceeding 58 mph large hailstone or produce tonardos

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