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99 Cards in this Set
- Front
- Back
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All gasses are almost completely _______________ to Sun's peak energy output |
transparent |
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________ and _______ are also transparent to the Earth's peak energy output |
02 and N2 |
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__________________ aren't transparent to the Earth's peak energy output |
greenhouse gasses |
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Definition of temperature |
Measure of the average speed of all the molecules in a substance |
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_____________ air expands, __________ air contracts |
Warm
Cool |
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What two things cause general temperature variations? |
Angle of the Sun's rays and length of day light hours aren't constant
Earth is covered with many different surface types that absorb energy differently |
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Atmosphere is always trying to get to ______________ |
equilibrium |
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The ___________ the latitude, the greater the yearly variation in temperature. |
greater |
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Proximity to large bodies of water can affect the.... |
temperature range |
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layers of the atmosphere are defined by __________ profile |
temperature |
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all of weather occurs in the... |
troposphere |
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temperature inversion |
any time air temperature goes up as you go up |
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Definition of pressure |
force per unit area applied by the air |
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air always moves from _________ pressure to ___________ presure |
higher to lower |
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The greater the change in pressure over a given distance, the ____________ the wind |
faster |
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Air pressure ______________ rapidly with height |
decreases |
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The closer the spacing of the isobars, the __________ the winds. This is due to a strong pressure gradient |
faster |
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What is the heat associated with phase change? |
Latent heat |
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What is the force per unit area applied only by the water vapor molecules? |
vapor pressure |
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Vapor pressure can/can not be measured directly |
can not |
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How is vapor pressure calculated? |
based on the dewpoint temperature |
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What is the vapor pressure when the atmosphere can no longer hold any more water vapor without condensing some out as a liquid? |
saturation vapor pressure |
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What is the temperature to which the air must be cooled for condensation to begin? |
dew point temperature |
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When the temperature is close to the dewpoint temperature, you get ________ air.
When the temperature is far from the dewpoint temperature, you get _____ air. |
humid
dry |
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What is the measure of the actual amount of moisture in the air relative to its maximum capacity? |
relative humidity |
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What is the equation for Relative Humidity? |
RH = VP/SVP x 100 |
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Two things to do change the relative humidity |
1. add or subtract water vapor
2. raise or lower the temperature |
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What happens to the relative humidity if you heat the air up? |
It decreases |
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What happens to the relative humidity if you cool the air off? |
It increases |
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What happens to the relative humidity if you add more water vapor? |
It increases |
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The hotter it is, the more/less water vapor the air can contain |
more |
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It is easier to saturate cold/warm air. |
cold |
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What is the primary instrument used to collect upper air data? |
rawinsonde (weather balloon) |
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What do weather balloons typically measure? |
Temperature
dewpoint temperature
pressure
windspeed and direction |
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What is the international standard for time? |
Universal Coordinated Time UTC |
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CST is ____ hours behind UTC |
six |
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What are the advantages and disadvantages of low-earth orbit satellites? |
very high spatial resolution
but
only see a small area of earth's surface at any given time |
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What are the advantages and disadvantages of geosynchronous orbit satellites? |
looks at the same point on the equator and sees nearly half of the Earth
but
not very high resolution |
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Visible imagery satellites measure reflected.... |
visible sunlight
meaning there are no images at night!! |
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Bright objects on visible imagery are objects with high/low albedo. |
high
snow, thick clouds, ice caps |
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Dark objects on visible imagery are objects with high/low albedo. |
low
vegetation, land, thin clouds, oceans |
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Infrared imagery measures... |
the emitted IR radiation
the temperature of an object |
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Bright objects on infrared imagery are hot/cold |
cold...
high clouds |
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Dark objects on infrared imagery are hot/cold |
hot
low clouds, surface, and snow |
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Hotter objects emit more/less radiation than colder objects |
more |
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Water vapor imagery measures... |
emitted radiation from water vapor
tells us the moisture content of the air |
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Bright objects on w. vapor imagery shows high/low water vapor content |
high
thunderstorms and thick clouds |
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Dark objects on w. vapor imagery shows high/low water vapor content |
low
cold, clear and dry areas |
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What does satellite measure? |
Cloud properties |
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What does radar measure? |
precipitation |
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How many radars are in the NEXRAD radar system? |
158 |
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What is radar reflectivity? |
the reflection of microwaves off the rain drops (echo) |
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More bigger drops = _________ radar reflectivity = more/less intense precipitation |
higher
more |
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55 DBZ often indicates... |
hail |
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What five things does radar measure (about precipitation)? |
presence and coverage
location
intensity
amount
wind speed and direction |
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What is the frequency of collection for radar? |
constant |
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How is radar data viewed? |
Color coded maps that show intensity of the precipitation |
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What is clear air mode? |
Radar gets echoes from birds, bugs, dust, turbulence in moisture content and even light snow.
Commonly called "ground clutter" |
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What is preciptation mode? |
Designed to see rain
Gets radar echoes from precipitation |
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What colors determine if the precipitation is going toward/away from the radar? |
Red = going away
Green (Blue) = going toward |
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Characteristics of the extra-tropical cyclone |
Winds and clouds circulate in a counterclockwise direction
Comma shape, with a dry slot
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Typical tracks of extra-tropical cyclones affecting North America |
typically track from southwest to northeast
time to cross the US = 2-5 days |
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Alberta Clipper |
Bring very cold air and blizzards to the northern plains of the US |
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Colorado Low |
bring rain to Champaign |
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Ark-La-Tex Low |
Track to the south of Champaign, we get snow |
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Gulf Low |
brought about Storm of the Century in 1993 |
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Hatteras Low |
nicknamed nor' easter due to strong onshore NE winds |
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What are the two primary forces that control the wind? |
pressure gradient force
Coriolis force |
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Pressure gradient force |
Change in pressure/change in distance |
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For a high pressure system to strengthen, ___________ aloft must be greater than _____________ at the surface |
convergence
divergence |
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For a low pressure system to strengthen, ___________ aloft must be greater than _____________ at the surface |
Divergence
Convergence |
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Convergence aloft creates ________ pressure system |
high |
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Divergence aloft creates _______ pressure system |
Low |
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Convergence aloft creates rising/sinking air above a high/low pressure system |
sinking
high |
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Divergence aloft creates rising/sinking air above a high/low pressure system |
rising
low |
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What is the jet stream? |
A band of strong winds that encircle the earth in a wave-like pattern that moves from the west to the east
exists where warm air meets cold
creates and destorys high and low pressure systems |
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What is the size of the jet stream? |
200-300 miles wide
1 mile thick
1000s of miles long |
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What is the location of the jet stream? |
30 N - 80 N |
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What are regions of the jet stream with exceptionally fast winds? |
jet streaks |
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The _______________ of a layer in atmosphere is governed by the mean air temperature between the top and bottom of the layer |
thickness |
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Key feature of wind in the jet stream |
fast around the ridge, slow around the trough |
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Being in the ridge of the jet stream creates a ______ pressure system |
high |
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Being in the trough of the jet stream creates a ______ pressure system |
low |
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Can liquid water remain a liquid at temperatures below 32 F? |
yes, supercooled water |
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Supercooled water |
water in a liquid phase with a temperature of < 0 C
can remain a liquid up to -40 C |
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freezing rain |
supercooled water that freezes on contact with a surface that is below freezing |
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all ice is _____________ in its molecular structure |
hexagonal |
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to lock into the lattice structure, ice __________ serve as the site onto which ice crystals begin to grow |
nuclei |
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ice nuclei are _______ and only effective at what temperatures? |
rare
lower than -15 C |
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Without __________________, the water will remain liquid, even though its temperature is below freezing |
ice nuclei |
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Criteria for freezing rain development |
air near surface that is below freezing
warm layer of air in the lower levels of the troposphere |
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3 ways blizzards can occur in north central US |
from Rocky Mts channeling cold air south from Canada
from very cold dome of air developing at surface that creates a high pressure system due to long Canadian nights
strong winds from ETC |
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The colder it gets, the bigger/smaller the liquid/snow ratio |
bigger |
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is there a snow depth requirement for a blizzard? |
no, but there is a wind speed requirement |
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Heaviest snow bands are... |
to the NW of the low pressure system about 150 miles from the low-pressure center |
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where do the most blizzards occur? |
North Dakota |
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4 criteria for a blizzard warning |
falling or blowing snow
35 mph winds
reduced visibility to 1/4 mile or less
first 3 lasting for at least three hours |
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4 ways the human body loses heat |
conduction
radiation
convection
latent heating |
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what temperature does the NWS say is a dangerous situation? |
-18 F |
