• Shuffle
    Toggle On
    Toggle Off
  • Alphabetize
    Toggle On
    Toggle Off
  • Front First
    Toggle On
    Toggle Off
  • Both Sides
    Toggle On
    Toggle Off
  • Read
    Toggle On
    Toggle Off
Reading...
Front

Card Range To Study

through

image

Play button

image

Play button

image

Progress

1/122

Click to flip

Use LEFT and RIGHT arrow keys to navigate between flashcards;

Use UP and DOWN arrow keys to flip the card;

H to show hint;

A reads text to speech;

122 Cards in this Set

  • Front
  • Back
Troposphere
- 8 km in poles, 18 km in equator.
- Area where most of weather exists.
Tropopause
- Layer between troposphere and stratosphere.
Relative Humidity
- [(vapor pressure) / (saturation vapor pressure) ] x 100%.
Phase Change
- melting & evaporation; condensation & freezing; sublimation & deposition.
Latent Heat
- Energy required/release for phase change.
Polar Jetstream
- Uneven solar heating of Earth from equator to poles drives the weather and jets at 200-300 mb.
- Located around 50 N/S latitude.
Subtropical Jetstream
- Uneven solar heating of Earth from equator to poles drives the weather and jets at 200-300 mb.
- Located around 25 N/S latitude.
Tropospheric Fold
- North of each jetstream stratospheric air descends in a narrow zone.
Sea Level Pressure
- The weight of a column of air over a unit area.
- Average sea level pressure (14.7 lbs/in^2, 29.92" Hg, 1013.25 mb, 1013.25 hPa) at 15 C (59 F)
World Record Hottest Temperature
136 F at El Azizia, Libya (9/13/1922)
US Record Hottest Temperature
134 F at Death Valley, CA (7/10/1913)
World Record Coldest Temperature
-129 F at Vostok, Antarctica (7/21/1983)
US Record Coldest Temperature
-80 F at Prospect Creek, AK (1/23/1971)
Dew Point
- The temperature at which condensation will occur.
Vapor Pressure
- The amount of water vapor contained at a certain pressure at which the dew point resides.
Supercooled
- Pure water will not freeze until temp reaches -40 C; water at temps below 0 C are said to be supercooled; ice nuclei (must have a crystal lattice structure similar to that of ice) become active when temp drops to -10 C to -15 C.
Graupel
- Tiny, soft ball of ice; ice crystals collide with supercooled droplets.
Hail
- Continued growth of graupel (wet & dry).
Snowflakes
- Ice crystals collect other ice crystals.
Ice Pellets
- Frozen raindrops.
- AKA Sleet.
Wind Speed Conversion
- 1 knot = 1.15 mph.
- 1 knot = 0.51 m/sec.
Heating Degree Day
- A measure of energy consumption.
- Heating season runs from July 1st through June 30th of the following year.
Cooling Degree Day
- A measure of energy consumption
- Air conditioning season runs from Jan. 1st through Dec. 31st of the current year.
Growing Degree Day
- Uses a different base temp for each crop; accumulated GDDs indicate when a crop is ready for harvest.
Synoptic Meteorology
- The analysis of weather data for forecasting & research.
Time Zones (GMT & Conversion)
- The international standard for meteorology is Universal Coordinated Time (UTC), also known as Greenwich Mean Time (GMT) and Zulu Time (Z).
- (GMT time) + (sum/difference of hours away) - (12, if more than 12).
EST/EDT
- EST is 5 hours behind GMT.
- EDT is 4 hours behind GMT.
ASOS
- Automated Surface Observing System.
- Used by NOAA.
AWOS
- Automated Weather Observing System.
- Used by FAA/DOD.
METAR (Data & Acronym)
- Meteorological Aviation Reports.
- **Notable data to come.**
Rawinsondes
- A balloon-borne instrument system that measures temperature, dew point temperature and pressure; by tracking the balloon with RADAR, the wind direction and speed can be determined.
Radiosondes
- a balloon-borne instrument system that measures temperature, dew point temperature and pressure.
Soundings
- Rawinsonde data (temp, dew point, pressure and wind) is plotted on a thermodynamic diagram (e.g., Skew-T/Log P).
Surface Charts
- All barometric pressure readings are "reduced" to sea level (SLP) in order to produce a mean sea level surface analysis.
Constant Pressure Charts
- Charts of constant pressure, that show the height contours of the pressure in meters.
Constant Altitude Charts
- Charts of constant altitude, that show the pressure in mb.
Standard Pressure Levels (ft./m.)
- 850 mb 5,000 feet 1,500 m
- 700 mb 10,000 feet 3,000 m
- 500 mb 18,000 feet 5,500 m
- 300 mb 30,000 feet 9,000 m
- 250 mb 35,000 feet 10,500 m
- 200 mb 39,000 feet 12,000 m
Height/Distance Conversion
- 1 meter = 3.281 feet
- 1 degree latitude = 60 nautical miles (69 statute miles)
850 mb Chart
- Location of the low-level jet (which transports heat and moisture northward); useful in identifying frontal boundaries; the 0° C isotherm provides a crude rain/snow line; this becomes a "fictitious" level for those places with elevations above 1500 m (e.g., Denver, CO).
700 mb Chart
- This level intersects many clouds, thus moisture distribution is important; dry intrusions at this level are a precursor to severe weather; weak surface low pressure systems will be "driven" by the flow at this level.
Low-Level Jet
- Transports heat and moisture northward.
500 mb Chart
- This level is used to determine the location of short waves and long waves (associated with ridges and troughs in the air flow pattern); absolute vorticity is plotted at this level; moderate to strong low pressure systems will be "driven" by the flow at this level.
300, 250, 200 mb Charts
- These levels are located near the top of the troposphere and in the lower stratosphere; the jetstream winds and jetstreaks are found near these levels; important levels for confluence/difluence.
Source Regions
- A large expanse (several hundred thousand square km) where air can stagnate (light winds) long enough to "acquire" the thermal and moisture properties of the underlying surface.
Jetstreaks
- A core of extremely high winds within the jet stream caused by locally strong pressure gradients; usually found on the upper-level constant pressure charts (300 mb, 250 mb, 200mb).
Bermuda High
- In summer, when the oceans are cooler than the continents, this semi-permanent high pressure area forms over the Bermuda area.
Pacific High
- In summer, when the oceans are cooler than the continents, this semi-permanent high pressure area forms over the Pacific Ocean area.
Icelandic Low
- In winter, semi-permanent low pressure is formed over Iceland/Greenland area.
Aleutian Low
- In winter, semi-permanent low pressure is formed over Alaska.
Continental Polar (cP)
- Cold (sometimes, bitterly cold) and dry; stable.
- Originate over the ice-and snow-covered regions of northern Canada & Alaska, where long, clear nights allow for strong radiational cooling of the surface.
- In winter, outbreaks of bitterly cold air into continental U.S. (e.g., "Texas Blue Norther"); will create lake effect snow in late autumn and winter.
- In summer, can provide relief from heat waves.
Continental Arctic (cA)
- Much colder than Continental Polar (cP).
- Cold (sometimes, bitterly cold) and dry; stable.
- Originate over the ice-and snow-covered regions of northern Canada & Alaska, where long, clear nights allow for strong radiational cooling of the surface.
- In winter, outbreaks of bitterly cold air into continental U.S. (e.g., "Texas Blue Norther"); will create lake effect snow in late autumn and winter.
- In summer, can provide relief from heat waves.
Maritime Polar (mP)
- Cool and moist; unstable.
- Form over high latitudes over ocean water; usually a modified cP air mass from northern Asia or AK.
- Affects west coast of U.S.; most often from Pacific Ocean.
- Atlantic mP are often colder than Pacific mP, due to smaller size of water expanse.
Maritime Tropical (mT)
- Warm and moist; usually unstable; form over sub-tropical bodies of water.
- Gulf of Mexico, Caribbean Sea and western Atlantic Ocean all affect eastern and central U.S.
- In Winter, mT air is usually confined to the Gulf Coast states.
- In Summer, mT air can provide moisture for "monsoon" over SW-U.S.
Pineapple Connection
- Sub-tropical jet stream sends ample mT air from Hawaii to Western U.S. and is associated with "El Nino"; heavy rains and flooding in central and southern CA.
Anafront
- Associated with warm front.
- front with clouds and precip in the cold air, as with nearly all warm fronts; precip behind a cold front.
Continental Tropical (cT)
- Hot, dry stable air aloft; conditionally unstable surface air; usually comes down from the southern Rockies & the northern Mexican Plateau.
- Marked by large diurnal temperature ranges (i.e., hot days and cool nights)
- Can set up a "dry line" over south-central U.S. (especially TX & OK).
Isotherms
- Lines of constant temperature.
Isodrosotherms
- Lines of constant dew point.
Frontogenesis
- When a frontal boundary forms or becomes stronger due to increased temperature contrast across the front.
Frontolysis
- When a frontal boundary weakens and dissipates due to a decrease in temperature contrast across the front.
Katafront
- Associated with warm and cold fronts.
- Front with clouds in the warm air; precipitation ahead of a cold front.
Cold Front
- Temps will begin to fall behind front; front located at leading edge of baroclinic zone.
- Dew point temps turn sharply colder (less humid).
- Wind has SE to SW component in advance; SW to NW behind.
- Pressure falls in advance; sharply rises following frontal passage.
- Cb/Cu (TSRA/SHRA) can precede/accompany front; Sc (SHRA) or CLR can follow.
Warm Front
- Cooler temps in advance of front; sharply warmer following frontal passage.
- Dew point temps cooler in advance of front; higher following frontal passage.
- Wind has N to SE component in advance; SE to SW behind.
- Pressure falls steadily as front approaches; rises following front, but may fall again.
- OVC (-RA/-SN) in advance of front; partial clearing behind (sometimes Cb/TSRA).
Stationary Front
- Sharp temperature contrast on both sides of front.
- Sharp dew point contrast on both sides of front.
- Wind E to SW on warm side of front; NW to NE on cold side of front.
- Pressure remains fairly steady.
- Katafront: clouds + precip on warm side; Anafront: clouds + precip on cold side.
Occluded Front
- Usually has cool/cold air on both sides of front; cold<warm>cool; cool<warm>cold.
- Dew point temps usually within a few degrees of temps (i.e., high RH).
- Sharp wind shift from E to S component to W to N.
- Pressure falls steadily in advance, then rises steadily after passage.
- Usually OVC, with light precip (-RA/-SN/-PL/-FZRA) on both sides of front.
Dry Line
- Warm to hot temps on both sides of dry line.
- Much lower (drier) dew points on west side; higher dew points on east side.
- Wind E to SW in advance of dry line (warm/humid); SW to NW behind (warm/dry).
- Pressure falls in advance; rises behind.
- Many times just CLR, but can initiate severe weather (+TSRA/+FC).
Upper-Level Front
- No significant change in surface temps.
- No significant change in surface dew points.
- Slight shift in surface wind direction as it passes; from E to SE, to perhaps SE to SW.
- Pressure falls in advance; rises behind; a surface trough may be noted.
- Sharp line of TSRA/SHRA exists, with CLR/SCT to the west of the line.
Cold Air Damming
- Occurs east of a mountain range; can distort front.
Convergence
- Always associated with increasing surface pressure, since the mass per unit area (i.e., weight) of the air column is increasing with time.
Divergence
- Always associated with decreasing surface pressure, since the mass per unit area (i.e., weight) of the air column is decreasing with time.
Confluence Flow
- Places where something is coming together (e.g., height contours on a constant pressure chart); mass increase or decrease not a factor.
Difluence Flow
- Places where something is moving apart (e.g., height contours on a constant pressure chart); mass increase or decrease not a factor.
Geostrophic Wind
- Air flows parallel to height contours on an upper-level chart.
Gradient Wind Balance
- Actually an "imbalance" between the pressure gradient force (PGF) and the Coriolis Force (CF); as air moves CCW into a curved flow pattern around a low pressure center, it will accelerate around the low at speeds less than the geostrophic wind flow (GWF); as air moves CW into a curved flow pattern around a high pressure center, it will accelerate around the high at speeds greater than the geostrophic wind flow (GWF).
Upper-Level Divergence
- The acceleration of air from the base of the trough to the crest of the ridge.
Upper-Level Convergence
- The deceleration of air from the crest of the ridge to the base of the trough.
Low Pressure
- Surface convergence.
High Pressure
- Surface divergence.
Adiabatic Process
- A process with no exchange of heat with parcel and environment.
Diabatic Process
- A process that does involve a transfer of heat energy.
Dynamic
- Curvature and jetstreak effects associated with force imbalances.
Thermodynamic
- Heating and cooling effects.
Warm Air Advection
- WAA.
- Warmer isotherms are coming in the flow of geostrophic wind.
- Surface -> 850 mb maps.
Cold Air Advection
- CAA.
- Colder isotherms are coming in the flow of geostrophic wind.
- Surface -> 850 mb maps.
Cyclonic Vorticity Advection
- CVA
- Cyclonic spin read at 500 mb.
Anticyclonic Vorticity Advection
- AVA
- Anticyclonic spin read at 500 mb.
Baroclinic Zone
- A tightly packed "thermal ribbon" of isotherms or 1000-500 mb thickness contours.
Triple Point
- Where the WARM FRONT, COLD FRONT and OCCLUDED FRONT all meet.
Solenoid
- The "box" formed by the intersections of the advecting quantity (e.g., the wind) and the property begin advected (e.g., isotherms, thickness, vorticity, etc.).
Advection Methodology
- Once you have identified a "solenoid", figuratively place yourself in the "box" facing the wind; note the values of the parameter being advected in front and behind you; if the values coming at you are increasing then you have identified the type of "advection" ... WAA or CVA ... depending on what map you are analyzing; if the values coming at you are decreasing in value, then you have identified ... CAA or AVA ... again depending on what map you are analyzing.
Polar Front
- A semicontinuous global boundary separating cold polar air from warm subtropical air.
Polar Front Theory
- Begins with stationary polar front; high pressure north and south of the pressure trough (i.e., stationary front) sets up cyclonic wind shear.
- A wavelike "kink" forms on the front, in response to an approaching short wave; the low that forms on the front is known as a "frontal wave" or "incipient cyclone".
- In about 12-24 hours, a fully developed "open wave" forms; low now has several closed isobars around its center; precipitation develops in advance of the warm front and in a narrow band along the cold front; a "warm sector" develops between the two fronts.
- The low "deepens" (i.e., central pressure drops); the wind circulation increases, as more and more closed isobars encircle the low center; the faster moving cold front begins to overtake (i.e., "occlude") the slower moving warm front; clouds and precip cover a large area.
- The system reaches its most intense point and it begins to "occlude" as the cold front overtakes the warm front; the low begins to "fill" (i.e., central pressure rises) and the dissipation stage begins; clouds and precip in "comma" shape; a secondary low may develop on the "triple point" (i.e., where all three fronts meet) and go through a "life history" of its own.
- The system dies out, as it is far removed from the "warm sector" and the supply of energy provided by the rising warm, moist air; this entire "life cycle" can last from a few days to over a week.
Baroclinic
- Isotherms cross height contours, creating areas of warm air advection (WAA) and cold air advection (CAA); air density does vary.
Baroclinic Instability
- Occurs in a flow pattern when warmer air rises and colder air sinks; this sets up areas of convergence and divergence, which in turn intensifies the corresponding surface high and low pressure areas.
Warm Conveyor Belt Model
- The warm conveyor belt originates at the surface in the warm sector (mT air mass) and flows northward, slowly rising along the sloping warm front, gradually turning toward the northeast or east, parallel to the upper wind flow; the water vapor in the rising air condenses, forming clouds and precipitation.
Cyclogenesis
- The development or strengthening of a mid-latitude cyclone.
Bomb Cyclogenesis
- Defined to be a pressure drop of 24 mb in 24 hours, normalized at 60 deg N Latitude (Bergen, Norway); translates to about 19 mb in 24 hours at 40 N.
Superbomb Cyclogenesis
- Defined to be a pressure drop of 24 mb in 12 hours, normalized at 60 deg N Latitude (Bergen, Norway); translates to about 19 mb in 12 hours at 40 N.
Storm Tracks
- Gulf Low and Hatteras Low (Nor'easters); Texas Low; Colorado Low; Gulf of Alaska Low.
Alberta Clipper
- The most common storm track.
Rule of Thumb
- Surface cyclones tend to move in direction of 500 mb flow at about half the speed of the 500 mb winds. (avg summer speed: 16 knots; avg winter speed: 27 knots).
Planetary Waves ("Rossby")
- Longwave troughs and ridges that encircle the hemisphere; anywhere from three (3) to six (6) longwaves at any time around the hemisphere; wavelength (trough-to-trough or ridge-to-ridge) in the thousands of kilometers; tend to be stationary or move eastward at less than 4 degrees Longitude per day (i.e., about 8 knots) or move westward (i.e., retrograde).
Shortwaves
- Smaller disturbances or ripples imbedded in the longwaves; tend to move eastward at a speed proportional to the average wind flow at 700 mb; when short wave drops into longwave trough, constructive interference causes trough to deepen.
Barotropic
- Isotherms are parallel to height contours; air density does not vary.
Equivalent Barotropic
- When a barotropic pattern is moving (e.g., cut-off low).
Cold Conveyor Belt Model
- The cold conveyor belt originates at the surface to the northeast of the surface low and north of the warm front (mP); it moves slowly westward from off the ocean; as it moves into the vicinity of the surface low, rising air gradually forces the cold conveyor belt upward, turning as it ascends, to form the comma-shaped cloud pattern; part of the airstream may rise high enough to get caught in the southwesterly flow aloft and swings northeastward, thus splitting the cold conveyor belt.
Dry Conveyor Belt Model
- This upper-level airstream slowly descends from the northwest behind the surface cold front, where it brings general clearing weather; if a branch of the dry air sweeps into the storm, it produces a clear air that "sharpens" the comma-head, creating a "dry slot".
Blizzard of 1993
- Known as "The Storm of the Century"; the central pressure dropped to a minimum of 960 mb (28.35"), a pressure comparable to a Category 3 hurricane, but the surface winds were more like a Category 1 hurricane in places; the storm produced 27 tornadoes (mostly in FL, where a "storm surge" was noted as the low moved ashore from off the NE-Gulf of Mexico); the storm produced deep snow from AL & GA, north to eastern Canada; every major airport along east coast was shut down; over 3 million people lost power; an estimated $800 million in damage and 270 storm-related deaths.
Vorticity
- A measure of SPIN, defined as TWICE the angular rate of rotation of an object about a vertical axis.
Earth Vorticity
- The spin imparted to the air by the rotating Earth (rotation around a local vertical); is dependent on LATITUDE.
Relative Vorticity
- The counter-clockwise (CCW) or clockwise (CW) circulation of weather systems. CCW (cyclonic) rotation is considered "+" ... same as Earth; CW (anticyclonic) rotation is considered to be "-"; consists of two parts: relative vorticity due to curved flow and that due to wind shear.
Curved Flow
- Parcels acquire relative vorticity when they encounter curved flow; CCW spin (cyclonically, "+") through the base of a trough; CW spin (anticyclonically, "-") through the crest of a ridge.
Wind Shear
- Parcels acquire relative vorticity when they encounter horizontal differences in wind speeds; CCW spin (cyclonically, "+") when the wind speeds are greater to the south of the parcel; CW spin (anticyclonically, "-") when the wind speeds are greater to the north of the parcel. (Sometimes referred to as: "shear vorticity.").
Absolute Vorticity
- The sum of EARTH VORTICITY plus RELATIVE VORTICITY.
Lee Cyclogenesis
- the development of a lee-of-the-mountain trough.
Potential Vorticity
- = ABSOLUTE VORTICITY (earth + relative) / DEPTH.
Lee-Side Low
- As the air descends the lee mountain slope, the column stretches. Once again, if the depth increases, so must the relative vorticity, which must also increase (PV is conserved). This causes the air to now turn cyclonically, thus creating a trough of low pressure.
Zonal Flow
- When the upper level winds are parallel or nearly parallel to the lines of latitude the wind pattern.
Meridional Flow
- The jet stream will have highly amplified troughs and ridges.
RAOB
- Rawinsonde observation.
- **Notable data will be added.**
Veering
- A wind that turns clockwise with height.
- Anticyclonic.
Backing
- A wind that turns counter-clockwise with height.
- Cyclonic.