# Shared Flashcard Set

## Details

ATOC 2
6,7,8,9
79
Environmental Studies
03/08/2011

## Additional Environmental Studies Flashcards

Term
 convectiont
Definition
 air rising rapidly in a way that causes storms
Term
 air parcel
Definition
 distinct blob of air
Term
 Stable
Definition
 if the parcel is displaced vertically, it will RETURN to its original position
Term
 Neutral
Definition
 if the parcel is displaced vertically it will REMAIN in its new position
Term
 Unstable
Definition
 if the parcel is displaced vertically, it will accelerate away from its new position
Term
Definition
 process in which a parcel of air does not mix with its environment or exchange heat energy with its environment -air parcel will either compress to heat or condense to cool -expand as they rise, compress as they fall (pressure)-use lapse rate to predict temperature
Term
 Lapse rate
Definition
 the rate at which temperature decreases (lapses) with increasing altitude
Term
 Dry adiabatic lapse rate
Definition
 -the rate at which an air parcel that is not saturated will cool10C/km
Term
 Adiabatic rate for SATURATED parcels
Definition
 rate at which a saturated parcel will warm as it falls -lower atmosphere: 4C/km-In the middle atmosphere: 2C/km
Term
 Moist adiabatic lapse rate
Definition
 -determined by the combined effects of expansional cooling and latent heat -lower= 10C/km-4C/km= 6C/km-Middle: 8C/km-near tropopause: about 10C/km
Term
 Environment
Definition
 the atmosphere outside the parcel
Term
 Environmental lapse rate
Definition
 the rate at which temperature decreases with increasing altitude-varies from 4C/km-9C/km
Term
 density and temperature
Definition
 in the atmosphere, a parcel of air is less dense that its environment if the parcel is warmer than the environment
Term
 Determining stability of air parcels
Definition
 we determine stability by comparing the parcel's temperature after lifting to the temperature of the surrounding environment-If its warmer, it will continue to rise-if its cooler, it will sinkboth unstable
Term
 stable environment
Definition
 -if the temperature of the air parcel is different than that of the air, it will sink/rise back to its original position
Term
 Neutral stability
Definition
 a parcel will have the same temp as its environment at all levels only if the environmental lapse rate is 10C/km
Term
 Conditionally unstable
Definition
 the condition required for instability is that the displaced parcel of air be saturated
Term
 condensation level
Definition
 the level where saturation first occurs-seen at cloud base
Term
 Lifting condensation level
Definition
 the air is lifted to cloud base (where saturation occurs)
Term
 level of free convection
Definition
 level at which an air parcel first becomes buoyant (its temperature first exceeds the surrounding environment's temperature)
Term
 Lifting mechanisms
Definition
 what lifts air parcels or causes them to rise in the atmosphere
Term
 Cold Front
Definition
 the boundary between a cold airmass and warm airmass when the cold air is advancing forward, lifting the warmer airmass
Term
 Sea Breeze
Definition
 a circulation that develops along shore lines during daytime in which warm air rises over land and moves shoreward aloft, while cool air offshore descends and moves onshore to replace the warm air
Term
 upslope storm
Definition
 a snowstorm along the east slope of the rocky mountains caused by air flowing westward across the plains and up the slope of the rockies
Term
 Convergence
Definition
 net inflow of air molecules into a region of the atmosphere with the result of increasing surface pressure. convergence can be caused by changing wind speeds and or changing direction of air flow
Term
 Lifting Index
Definition
 a measure of atmospheric stability, defined as the difference between the temperature of the environment at 500mb and an air parcel lifted from near the surface to 500mbLI= T(environment)- T(parcel)-the smaller the value, the warmer the parcel is relative to its environment-negative LI indicates instability
Term
Definition
 a horizontal or vertical change in pressure divided by the distance over which the change occurs
Term
Definition
 the force applied to a small parcel of air due to the variation of pressure over a small distance around the parcel -acts from high pressure (south) towards low pressure (north) perpendicular to isobars, accelerates air parcel northwards
Term
 Gravitational force
Definition
 attractive force between any two objects. earth's attractive force acting on air parcels has essentially a constant magnitude throughout the atmosphere and is directed toward the center of earth
Term
 Frictional Force
Definition
 drag force acting in a direction opposite the motion of air; always acts to reduce the speed of the flow
Term
 Coriolis Force
Definition
 an apparent force associated with the rotation of the Earth. causes air to deflect to the right of the motion in the northern hemisphere
Term
 Mechanical turbulence
Definition
 rapid variations of air motion that develop when moving air encounters obstructions associated with ground roughness
Term
 Thermal Turbulence
Definition
 turbulence created in the atmosphere by the ascent of buoyant air particles and subsequent mixing of the parcels with the environmental air
Term
 Wind Shear
Definition
 the rate of change of wind speed and/or direction with distance or altitude
Term
 Shear induced turbulence
Definition
 turbulence created in the atmosphere under conditions where winds increase rapidly with altitude
Term
 Boundary Layer
Definition
 layer of the atmosphere adjacent to the earth's surface where friction is important. depth can vary from a few hundred to a few thousand meters. also called friction layer
Term
 Angular momentum
Definition
 the product of an object's mass, rotational velocity, and radius from the axis about which it is rotatingAng Momentum= M x V x R
Term
 Newton's 2nd Law of Motion
Definition
 force exterted on an object equals its mass times its acceleration F= ma
Term
 Hydrostatic balance
Definition
 the balance between the upward pressure gradient force and the downward force of gravity
Term
 Geostrophic balance
Definition
 the balance between the pressure gradient force and the coriolis force
Term
 Geostrophic wind
Definition
 the wind that would exist if the pressure gradient and coriolis forces were in balance -in northern hemisphere, higher pressures are to the right of the geostrophic wind
Term
 jetstream
Definition
 band of strong winds that encircle the earth in the mid latitudes
Term
 Extratropical cyclone
Definition
 a large swirling low pressure system that forms along the jetstream due to imbalances between the coriolis and pressure gradient forces
Term
 convergence
Definition
 net inflow of air molecules into a region of the atmosphere with the result of increasing surface pressure. convergence can be caused by changing wind speeds and or changing direction of air flow -means increasing surface pressure because the mass/unit area increases with time
Term
 Divergence
Definition
 net outflow of air molecules from a region of the atmosphere with the result of decreasing surface pressure-can be caused by changes in wind speeds and directions
Term
 Low pressure center (cyclone)
Definition
 a location at which the pressure is less than the pressure at all surrounding points; generally associated with rising air, clouds, and precipitation
Term
 High pressure center (anticyclone)
Definition
 a location at which the pressure exceeds the pressure at all surrounding points; generally associated with subsiding air and clear skies
Term
 centripetal acceleration
Definition
 the acceleration toward the center of rotation experienced by a parcel of air in a rotational fluid
Term
Definition
 the state of curved flow in which the residual between the pressure gradient and coriolis forces exactly balances the centrifugal acceleration experienced by an air parcel
Term
 cyclonic curvature
Definition
 a curved pattern either in the pressure or height field in which air flows counterclockwise in the N Hemisphere
Term
 Anticyclonic curvature
Definition
 a curved pattern either in the pressure or height fields in which air flows clockwise in the n hemi
Term
 Curvature effect
Definition
 the creation of divergence within the jetstream due to the change of flow curvature from cyclonic flow (around trough) to anticyclonic flow (around a ridge)
Term
 jetstreak
Definition
 a region of exceptionally strong winds within the jetstream. convergence and divergence associated with jetstreaks directly influence the development of cyclones
Term
 Entrance region
Definition
 the side of a jetstreak in which the height gradient is increasing along the flow direction and the air is accelerating -air parcels displaced NORTHWARD in jetstream
Term
 Exit region
Definition
 the side of a jetstreak in which the height gradient is decreasing along the flow direction and air is deccelerating -air parcels displaced SOUTHWARD in jetstream
Term
 Curvature vs. Jetstreak (divergence and convergence)
Definition
 -South of the jetstream axis, divergence and convergence of jetstream and curvature counteract each other-north of the jetstream axis, the effects reinforce each other (same)
Term
 forces in friction layer
Definition
 -forces are imbalanced unlike geostrophic balance-friction disrupts balance by reducing wind speed- therefore coriolis force is reduced-since PGF is unchanged, it is the dominant force
Term
 friction and wind
Definition
 friction always acts to deflect wind direction to the left of the geostrophic wind direction, toward the low pressure side of isobars-friction always acts to turn the wind such that the flow has a component from higher to lower pressure
Term
 Diabatic Process
Definition
 a process in which an air parcel mixes with its environment and or exchanges heat with its environment
Term
 dynamic processes
Definition
 a process that involves forces
Term
 Thermodynamic Process
Definition
 a process involving heating or cooling of the atmosphere
Term
 Divergence (temp and pressure)
Definition
 -surface pressure decreases over time-low pressure system will develop-changes in the curvature in the flow, jetstreaks, and heating of the atmospheric column
Term
 Convergence (temp and pressure)
Definition
 high pressure systems are enhanced by convergence associated with the jetstream as these cool airmasses move out of their source regions -air flows clockwise aroudn the high, outward and away due to friction
Term
 Airmass
Definition
 a large body of air with relatively uniform thermal and moisture characteristics-typically several hundred thousand km in area-forms over relatively flat regions with homogenous surface characteristics
Term
 Arctic airmass
Definition
 an airmass characterized by bitter cold temperatures-considered arctic if it forms over the Arctic Ocean
Term
 Polar Airmass
Definition
 a large mass of cold, dry air that decelops over the northern part of the North American continent
Term
 Tropical Airmass
Definition
 an airmass that originates in tropical regions and is characterized by very warm to hot temperatures
Term
 Maritime airmass
Definition
 an airmass that has formed over the oceans and hence is relatively moist
Term
 Continental airmass
Definition
 airmass that forms over land and is characterized by low moisture content
Term
 Front
Definition
 boundary between airmasses of differing density-classified on the basis of the thermal and moisture characteristics of the airmasses, the direction of movement of the airmasses, and whether teh boundary between the airmasses in in contact with the ground or can only be found aloft
Term
 Cold Front
Definition
 the boundary between a cold airmass and a warm airmass when the cold air is advancing forward, lifting the warmer airmass-frontal boundary is typicall shaped like a dome -if the wind on the cold side blows towards the front, its a cold front-if warm air is unstable = thunderstorms
Term
 arctic front
Definition
 a cold front that marks the boundary of an extremely cold airmass in wintertime
Term
 warm front
Definition
 a boundary between airmasses where the cold airmass is retreating and the warm air is advancing at the surface -if warm air is conditionally unstable, thunderstorms will form -if the wind on the cold side blows away from the front its a warm front
Term
 Stationary Front
Definition
 a boundary between airmasses where the colder airmass is neither advancing nor retreating at the surface -unstable air can cause a line of thunderstorms-if the wind on the cold side blows along the front, its stationary
Term
 Occluded Front
Definition
 the airmass boundary that occurs when the air behind a cold front comes in direct contace with the cool air north or east of a warm front.-develops in the latter stages of an extraropical cyclone's life cycle when the cold front catches up to the warm front
Term
 cold occlusion
Definition
 an occluded front in which air behind the cold front is more dense (colder) than the air behind the warm front
Term
 Warm occlusion
Definition
 an occluded front in which air behind the cold front is less dense (warmer) than the air behind the warm front
Term
 Dry Line
Definition
 a front characterized by a sharp moisture contrast, but little temperature change. often found in the southern plains
Term
 Upper-level front
Definition
 a boundary between 2 airmasses that is present in the middle or upper-troposphere but does not extend to the earth's surface
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