radar palette home click doppler pre-warm frontal 1 ahead of wcb classic area for virga probability...
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Pre-warm Frontal 1Radar Palette Home Click Doppler
Ahead of WCB
• Classic area for virga• Probability of virga increases with strength and
dryness of the CCB and the strength and moisture of leading branch of the WCB
• Katabatic portion of warm front – winds veer above the warm frontal mixing zone
• Lack of precipitation in this area may limit Doppler interpretation
Click for the Conceptual Model and Explanation
Pre-warm Frontal 2Radar Palette Home Click Doppler
WCB
CCB
Warm Frontal Cross-section along Leading Branch of the Warm Conveyor
Belt (WCB)
Cold air in Cold Conveyor Belt (CCB) deep and dry
Moist portion of Warm Conveyor Belt (WCB) is high and veered from frontal perpendicular – katabatic tendency
Dry lower levels of WCB originate from ahead of the system and backed from frontal perpendicular
Mixing Zone
SurfaceWarm Front
Frontal slope is more shallow than the typical 1:200
Precipitation extends equidistant into the unmodified CCB
Precipitation extends further into the moistened, modified CCB
Increasing CCB Moistening
WCB oriented for
maximum frontal lift
WCB oriented for
less frontal lift
Virga Precipitation
Lower
Hydrometeor
Density
Common location for virga A
B
A B
WCB typically veers with height (it is after all, a warm front)
Link to ClassicExample
Pre-warm Frontal 3Radar Palette Home Click Doppler
Vertical Deformation Zone Distribution and the CBMSimplified Summary
C
C
WC
B
DCB
CCB
DCB
C
The WCB overrides the warm frontThe CCB undercuts the warm frontThe frontal surface overlies the mixing layerWind shear in the CCB is variable
Looking along the flow:•In WCB to the right of the Col expect veering winds with height – Katabatic warm front•In WCB approach to the Col expect maximum divergence – the eagle pattern with ascent and increasing pcpn•In WCB to the left of the Col expect backing winds with height – Anabatic warm front
Pre-warm Frontal 4Radar Palette Home Click Doppler
Vertical Deformation Zone Distribution and the CBMSimplified Flows in the Vertical
C
C
WC
B
DCB
CCB
DCB
CXrXcXl
Warm Sector: Winds veer withHeight and distance from Xr
Above frontal surface: Winds veer withHeight and distance from Xr
Below frontal surface: Winds could veer or back
Warm Sector: Winds back withHeight and distance from Xl
Above frontal surface: Winds back withHeight and distance from Xl
Below frontal surface: Winds could veer or back but likely veer
No
VW
S
Pre-warm Frontal 5Radar Palette Home Click Doppler
WCB to the Right of the Col
o
C
Warm frontal surface
Mixing layer
Cold CB
Warm CB
Within the WCB:•East of radar veering, warm advection•West of radar nil VWS
Within the CCB:•Probable Ekman spiral nearest surface•Probable cold advection above Ekman spiral
The Warm Right Wing Stoop CM
The eagles right wing is folded in as if it is about to swoop down.The left wing is still fully extended to catch the lift of the WCB.
Right W
ingLe
ft W
ing
Signature ofWarm Frontal surfaceWarm
advection
Radar Palette Home Click Doppler
Inactive or Katabatic Warm Front
Pre-warm Frontal 7Radar Palette Home Click Doppler
WCB Approaching the Col
o
C
Warm frontal surface
Mixing layer
Cold CB
Warm CB
Within the WCB:•East of radar veering, warm advection – katabatic warm front.•West of radar backing, cold advection – anabatic warm front.
Within the CCB:•Probable Ekman spiral nearest surface•Probable cold advection above Ekman spiral
The Warm Screaming Eagle CM
Both wings are fully extended to catch the lift of the WCB. This is a divergent signature.
Right W
ingLe
ft W
ing
Signature ofWarm Frontal surface
discontinuity
Pre-warm Frontal 8Radar Palette Home Click Doppler
BCAD
E
F
G
H
Need to emphasizeThe PPI nature of theDoppler scan- The cone
The Warm Screaming Eagle Conceptual Model
Radar Palette Home Click Doppler
Inactive or Katabatic Warm Front
Active or Anabatic Warm FrontApproaching the Col the Warm Front should have characteristics intermediate between the Anabatic Warm Front to the Left of the Col and the Katabatic Warm Front to the Right of the Col
Pre-warm Frontal 10Radar Palette Home Click Doppler
The PPI Virga Hole Signature – Typical in this Region of the CBCM• The difference between PPI and CAPPI displays can be used to advantage.
Each display must be consulted in an analysis of the atmosphere. This is most often seen in Doppler Radar which is typically a PPI display.
A
B
The Virga Hole signature is only revealed in the PPI radar display. The CAPPI cannot reveal the true extent of the precipitation if the precipitation lies above the CAPPI level. A cross-section can reveal the vertical distribution of the precipitation.The lowest level CAPPI display can be misleading as at longer ranges, the true level of the radar rises to follow the lowest PPI scan of the radar. This is depicted in this 1.5km CAPPI example. Click.
1.5km CAPPI
Cross-section fromA (left) to B (right)
3.5 PPI Virga Hole
Pre-warm Frontal 11Radar Palette Home Click Doppler
Under WCB
• Virga only likely on the leading edge of the WCB• The CCB is becoming increasingly moist• Frontal overrunning and isentropic lift is
increasing thus increasing the intensity of the precipitation process.
• Warm front becoming more likely Anabatic
Click for the Conceptual Model and Explanation
Pre-warm Frontal 12Radar Palette Home Click Doppler
WCB
CCB
Warm Frontal Cross-section along Central Branch of the Warm Conveyor
Belt (WCB)
Cold air in Cold Conveyor Belt (CCB) more shallow and moist
Moist portion of Warm Conveyor Belt (WCB) is thicker, higher and perpendicular to front
Lower levels of WCB have the same origin as the upper level of the WCB - frontal perpendicular
Mixing Zone
SurfaceWarm Front
Frontal slope is near the typical 1:200
Precipitation extends further into the moistened, modified CCB. Horizontal rain area begins to expand as CCB moistens.
Increasing CCB Moistening
WCB oriented for
maximum frontal lift
Virga Precipitation
Lower
Hydrometeor
Density
Common location for virga A
B
A B
WCB shows little directional shift with height. A greater WCB depth is frontal perpendicular
PrecipitationAt Surface
Pre-warm Frontal 13Radar Palette Home Click Doppler
Vertical Deformation Zone Distribution and the CBMSimplified Summary
C
C
WC
B
DCB
CCB
DCB
C
The WCB overrides the warm frontThe CCB undercuts the warm frontThe frontal surface overlies the mixing layerWind shear in the CCB is variable
Looking along the flow:•In WCB to the right of the Col expect veering winds with height – Katabatic warm front•In WCB approach to the right of the Col expect maximum divergence – the eagle pattern with ascent and increasing pcpn•In WCB to the left of the Col expect backing winds with height – Anabatic warm front
Pre-warm Frontal 14Radar Palette Home Click Doppler
WCB Approaching the Col
o
C
Warm frontal surface
Mixing layer
Cold CB
Warm CB
Within the WCB:•East of radar veering, warm advection – katabatic warm front.•West of radar backing, cold advection – anabatic warm front.
Within the CCB:•Probable Ekman spiral nearest surface•Probable cold advection above Ekman spiral
The Warm Screaming Eagle CM
Both wings are fully extended to catch the lift of the WCB. This is a divergent signature.
Right W
ingLe
ft W
ing
Signature ofWarm Frontal surface
discontinuity
Pre-warm Frontal 15Radar Palette Home Click Doppler
BCAD
E
F
G
H
Need to emphasizeThe PPI nature of theDoppler scan- The cone
The Warm Screaming Eagle Conceptual Model
Radar Palette Home Click Doppler
Inactive or Katabatic Warm Front
Active or Anabatic Warm FrontApproaching the Col the Warm Front should have characteristics intermediate between the Anabatic Warm Front to the Left of the Col and the Katabatic Warm Front to the Right of the Col
Pre-warm Frontal 17Radar Palette Home Click Doppler
CCB Doppler Diagnosis
A
B
C
The Beaked Eagle
•A is the radar site•AB is backing with height indicative of cold advection where really there should be veering with the Ekman Spiral•BC is veering with height indicative of warm advection•B is the front with the mixing layer hidden in the cold advection•This is a strong cold advection•The warm front will be slow moving or stationary
A
B
C
The Headless Eagle
•A is the radar site•ABC is all veering with height indicative of warm advection. Layer AB is apt to be partially the result of the Ekman Spiral•BC is veering with height indicative of warm advection•Where is the front and the mixing layer?•The cold advection is not apparent and the warm front will advance
Pre-warm Frontal 18Radar Palette Home Click Doppler
BCAD
E
F
G
H
WCB Doppler Diagnosis
Pre-warm Frontal 19Radar Palette Home Click Doppler
Pre-warm Frontal 20Radar Palette Home Click Doppler
Pre-warm Frontal 21Radar Palette Home Click Doppler
Behind WCB
• Virga much less likely• The CCB has become moist• Frontal overrunning and isentropic lift is
maximized thus maximizing the intensity of the precipitation process.
• Warm front is likely Anabatic
Click for the Conceptual Model and Explanation
Pre-warm Frontal 22Radar Palette Home Click Doppler
WCB
CCB
Warm Frontal Cross-section along Trailing Branch of the Warm Conveyor
Belt (WCB)
Cold air in Cold Conveyor Belt (CCB) even more shallow and more moist
Moist portion of Warm Conveyor Belt (WCB) is thicker, higher and backed from frontal perpendicular – anabatic tendency
Lower levels of WCB have the same origin as the upper level of the WCB
Mixing Zone
SurfaceWarm Front
Frontal slope likely steeper than the typical 1:200
Precipitation extends further into the moistened, modified CCB. Horizontal rain area expands rapidly as CCB moistened.
Increasing CCB Moistening
WCB oriented for
maximum frontal lift
Virga Precipitation
Lower
Hydrometeor
Density
Common location for virga A
B
A B
WCB probably backs slightly with height in spite of the warm air advection. A greater WCB depth is frontal perpendicular
PrecipitationAt Surface
Pre-warm Frontal 23Radar Palette Home Click Doppler
Vertical Deformation Zone Distribution and the CBMSummary
C
C
C
C
C
WC
B
DCB
CCB
DCB
C
Pre-warm Frontal 24Radar Palette Home Click Doppler
WCB to the Left of the Col
C
Warm frontal surface
Mixing layer
Cold CB
Warm CB
Within the WCB:•West of radar backing, cold advection•East of radar nil VWS
Within the CCB:•Probable Ekman spiral nearest surface•Probable cold advection above Ekman spiral
o
The Warm Left Wing Stoop CM
The eagles left wing is folded in as if it is about to swoop down.The right wing is still fully extended to catch the lift of the WCB.
Right Wing
Le
ft W
ing
Signature ofWarm Frontal surfaceWarm
advection
Signature ofWarm Frontal surface… odd?
Pre-warm Frontal 25Radar Palette Home Click Doppler
ABC
D
F
G
Pre-warm Frontal 26Radar Palette Home Click Doppler
Active or Anabatic Warm Front
Pre-warm Frontal 27Radar Palette Home Click Doppler
WCB Doppler Diagnosis – Diagnosis of the Eagle Wing
A
The Right Eagle Wing
•A is the radar site•BC is backing with height indicative of cold advection. •CD is veering with height indicative of warm advection•Larger angles subtended by the arcs BC and CD by the radar site A, are associated with strong thermal advections•A broad wing in the eagle is associated with strong advections
B
C
D B
C
D
A
The Left Eagle Wing
•A is the radar site•BC is veering with height indicative of warm advection. •CD is backing with height indicative of cold advection•Larger angles subtended by the arcs BC and CD by the radar site A, are associated with strong thermal advections•A broad wing in the eagle is associated with strong advections
Pre-warm Frontal 28Radar Palette Home Click Doppler
WCB Doppler Diagnosis – Diagnosis on the Gull Wing
A
The Right Eagle Wing
•A is the radar site•BC is backing with height indicative of cold advection. •CD is veering with height indicative of warm advection•Larger angles subtended by the arcs BC and CD by the radar site A, are associated with strong thermal advections•A narrow wing in the gull is associated with weak advections
B
CD B
C
DA
The Left Eagle Wing
•A is the radar site•BC is veering with height indicative of warm advection. •CD is backing with height indicative of cold advection•Larger angles subtended by the arcs BC and CD by the radar site A, are associated with strong thermal advections•A narrow wing in the gull is associated with weak advections
The Gull Conceptual Model - weaker thermal advections
Pre-warm Frontal 29Radar Palette Home Click Doppler
Pre-warm Frontal 30Radar Palette Home Click Doppler
Pre-warm Frontal 31Radar Palette Home Click Doppler
Doppler Oriented Reference Conceptual Models
Pre-warm Frontal 32Radar Palette Home Click Doppler
Doppler Analysis and Diagnosis Strategies
An operational guide to getting the most information from Doppler radar:
• Determining the actual wind direction• Determining wind backing and veering• Diagnosing spatial versus vertical wind
variations• The Screaming Eagle and Gull Patterns
Pre-warm Frontal 33Radar Palette Home Click Doppler
Diagnosis of the Conveyor Belts
• Wind direction and speed diagnosis should be completed independently in each conveyor belt
• Given the nature of isentropic flow, this is a prudent mode of diagnosis. Isentropic flows stay relatively separate and maintain their distinctive properties.
• The Doppler characteristics depicted in the CCB are separate from those in the WCB. When added, instructive patterns are revealed.
Pre-warm Frontal 34Radar Palette Home Click Doppler
Range Ring versus Radial Zero Velocity Doppler Lines
A
B
C
Range Ring Zero Lines
•A is the radar site•Zero Doppler Velocity line that follows a range ring like BC depicts velocity vectors that are:
•All at the same elevation•Depictions of horizontal wind differences – primarily directional wind shear
•Range Ring Zero Lines thus depict spatial wind difference (primarily directional shear)
A B C
Radial Zero Lines
•A is the radar site•Zero Doppler Velocity line that follows a radial from the radar like BC depicts velocity vectors that are:
•At ever increasing heights•Depictions of vertical speed shear wind differences (no directional shear)
•Radial Zero Lines thus depict vertical wind difference/shear
The real Doppler data is a combination of these two patterns
Pre-warm Frontal 35Radar Palette Home Click Doppler
Diagnosis of Wind Direction – Using the Zero Line
A
•A is the radar site•BC the zero line•Everywhere along the zero line the radial component of the real wind detected by Doppler must be zero – meaning the total wind must be perpendicular to the radar radial – or actually zero which is unlikely.
B
C
•Draw a radial line from the radar site to the zero line
•The wind must be either zero or the wind direction must be exactly perpendicular to the radial line
•The wind direction can be determined as blowing from the toward colours (blue) to the away colours (red) perpendicular to the radial
•Click now
Zero Line
In Doppler wind analysis always establish the layers where the zero line veers (turns clockwise with range/height) and layers where the zero line backs (turns counterclockwise with range/height. These are the thermal advection layers. The point of inflection between backing and veering separates these important analytical layers.
Pre-warm Frontal 36Radar Palette Home Click Doppler
Diagnosis of Vertical Windshear – Using the Zero line
AB
C
D
•Determine the wind at B. Draw a radial line from the radar site to the zero line at B. Click
•Determine the wind at C. Click
•The wind backs from B to C
•Determine the wind at D. Click
•The wind veers from C to D
Summary - Generalizations
Thermal Advection Intensity•The larger the angle subtended by the arc, the stronger the thermal advections.•The smaller the angle subtended by the arc, the weaker the advections.•This angle is independent of range from the radarThermal Advection Type•If the arc rotates cyclonically with height (increasing range) the arc is associated with warm advection.•If the arc rotates anticyclonically with height, the arc is associated with cold advection.
Note that the directional wind shear increases with the angle subtended by the arc – This angle does not change with range from the radar (directional shear).The angle subtended by the zero line arc is the directional wind shear component of the velocity vector shear.
Pre-warm Frontal 37Radar Palette Home Click Doppler
Diagnosis of Vertical Windshear – Using the Zero line
AB
C
D
The angle subtended by the counter-clockwise arc BC would be the same regardless of the exact location of C anywhere along the radial AC from the Doppler radar. The amount of backing with height is also independent of the location of C along the radial AC. The amount of wind shear (cold advection) is dependent only on the subtended angle and not the orientation of the arc.
AB
C
D
The angle subtended by the clockwise arc CD would be the same regardless of the exact location of D anywhere along the radial AD from the Doppler radar. The amount of veering with height is also independent of the location of D along the radial AD. The amount of wind shear (warm advection) is dependent only on the subtended angle and not the orientation of the arc. The thermal VWS is thus the angle subtended by the arc divided by the elevation change that this thermal advection occurred over. The following slide illustrates these concepts.
Pre-warm Frontal 38Radar Palette Home Click Doppler
Thermal Advections and Vertical Wind Shear
AB
C
AB
C
AB
C
•The angle subtended by the counter-clockwise arc BC is identical in 1, 2 and 3.•In 1, the backing winds occur over a short radial range and thus a short height interval.•The radial range difference increases for case 2 and is even more for case 3. The height interval for the Thermal VWS increases with the length of the radial AC from case 1 to case 3.•The Thermal VWS determined by dividing the direction shear (subtended angle dependent) by the height interval (difference between AC and AB=AD) that it occurs over, is strongest for 1 and weakest for 3. •As detailed, Thermal VWS is a combination of the size of the subtended angle and the radial range (AC-AB=AD) which when combined, is inversely proportional to the area CBD. •This could feasibly be automatically calculated in URP. I sincerely doubt if it is.
1.
2.
3.
D
D
D
Pre-warm Frontal 39Radar Palette Home Click Doppler
Thermal Advections and Vertical Wind Shear
•Which has the strongest Thermal VWS?•The smaller the area CBD, the more intense the Thermal VWS and thus the more intense the thermal advections.
AB
C
1.
D
AB
C
2.
D
AB
C
3.
D
For a given subtended angle:•the strongest Thermal VWS occurs with a Doppler Zero Line closely following the range rings•the weakest Thermal VWS occurs with a Doppler Zero Line closely following the radar radial lines
Similarly for a given height interval CD radial:•the strongest Thermal VWS occurs with the largest subtended angle•the weakest Thermal VWS occurs with the smallest subtended angle
Pre-warm Frontal 40Radar Palette Home Click Doppler
Diagnosis of Stability Trends
• Stability increases with:• Cold advection decreasing with height:
– Angle of Doppler arc backing counterclockwise decreasing (rate of cooling decreases) with height (range) increasing (Area CBD increasing),
• Warm advection increasing with height:– Angle of Doppler arc veering clockwise increasing
(rate of warming increases) with height (range) decreasing (Area CBD decreasing),
• Warm advection over cold advection:– Doppler arc veering clockwise with height (range)
over Doppler arc backing counterclockwise with height (range).
Pre-warm Frontal 41Radar Palette Home Click Doppler
Doppler Examples for Increasing Stability
AB
C1.
D
Stronger cold advection BCLevel C
Weaker cold advection CDStabilization
Level D
Level B
A
B C
2. D
Weaker warm advection BCLevel C
Stronger warm advection CDStabilization
Level D
Level B
AB
C
3. D
(Weak) Cold advection BCLevel C
(Strong) Warm advection CDStabilization
Level D
Level B
Note: Angles kept constant.Changing the Thermal Advection Intensity by changing the depth of the directional wind shear.
Pre-warm Frontal 42Radar Palette Home Click Doppler
Diagnosis of Stability Trends
• Stability decreases (Destabilization) with:• Cold advection increasing with height:
– Angle of Doppler arc backing counterclockwise decreasing (rate of cooling increases) with height (range)
• Warm advection decreasing with height:– Doppler arc veering clockwise with height (range)
under Doppler arc backing counterclockwise with height (range).
– Angle of of Doppler zero arc veering clockwise increasing (rate of warming decreases) with height (range),
• Warm advection under cold advection:
Pre-warm Frontal 43Radar Palette Home Click Doppler
Doppler Examples for Increasing Instability
AB
C2.
D
Stronger warm advection BCLevel C
Weaker warm advection BCDestabilization
Level D
Level B
A
B C
3.
D
(Strong) Warm advection BCLevel C
(Weak) Cold advection CDDestabilization
Level D
Level BNote: Angles kept constant.Changing the Thermal Advection Intensity by changing the depth of the directional wind shear.
AB
C
1.
D
Weaker cold advection BCLevel C
Stronger cold advection CDDestabilization
Level D
Level B
Pre-warm Frontal 44Radar Palette Home Click Doppler
Changing Stability by Changing the Angle of the Vertical Wind Shear
• As the angle subtended by the zero line increases, the amount of directional wind shear also increases.
• The directional wind shear must be divided by the height over which this shear occurs in able to determine the magnitude of the thermal advections.
• Generally, as the angle increases, so does the thermal advections. The angle of the zero line relative to the range rings is essential to use this technique in an operational setting.
Pre-warm Frontal 45Radar Palette Home Click Doppler
Doppler Examples for Increasing Stability
Note: VWS Depth kept constant. Changing the Thermal Advection Intensity by changing the subtended angle (amount) of the directional wind shear. Increasing the angle, decreases the enclosed area.
AB
C
1.
D
Stronger cold advection BCLevel C
Weaker cold advection CDStabilization
Level D
Level B
A
B C
2.
D
Weaker warm advection BCLevel C
Stronger warm advection CDStabilization
Level D
Level B
o o
Cold AdvectionDecreasing with Height
Stabilization
Warm AdvectionIncreasing with Height
StabilizationThe angles that the zero line makes with the range rings is the operational approach to employ.
CAA angle increasing with range/height.
WAA angle decreasing with range/height.
Pre-warm Frontal 46Radar Palette Home Click Doppler
Doppler Examples for Increasing Instability
AB
C
1.
D
Note: VWS Depth kept constant. Changing the Thermal Advection Intensity by changing the subtended angle (amount) of the directional wind shear. Increasing the angle, decreases the enclosed area.
Weaker cold advection BCLevel C
Stronger cold advection CDDestabilization
Level D
Level B
A
B
C2.
D
Stronger warm advection BCLevel C
Weaker warm advection CDDestabilization
Level D
Level B
o o
Cold AdvectionIncreasing with Height
Destabilization
Warm AdvectionDecreasing with Height
DestabilizationThe angles that the zero line makes with the range rings is the operational approach to employ.
CAA angle decreasing with range/height.
WAA angle increasing with range/height.
Pre-warm Frontal 47Radar Palette Home Click Doppler
• Consider the angle between the veering or backing arc and the radar range ring.
• If this angle increases (in time) from previous values then the rate of wind shear with height is decreasing, since height is a function of radial range. This must imply that for a given arc, the thermal advections have decreased.
• If this angle decreases (in space) along the arc then the rate of wind shear with height is increasing, since height is a function of radial range. This must imply that for a given arc, the thermal advections have increased.
• Track the angle the arc makes with the radar rings with both time (between scans) and in space along the trace of the arc… if the angle increases, then the associated thermal advections are decreasing.
Doppler Rate of Thermal Advections with Height
o
Pre-warm Frontal 48Radar Palette Home Click Doppler
Doppler Rate of Thermal Advections with Height
• For example:• A clockwise, veering arc associated with warm
advection vertical wind shear:• Indicates that the layer is becoming more stable
if the angle with the range rings decreases with range. (warm advection increasing with height)
• Indicates that the layer is becoming more unstable if the angle with the range rings increases with range. (warm advection decreasing with height)
Pre-warm Frontal 49Radar Palette Home Click Doppler
Doppler Rate of Thermal Advections with Height
• For example:• A counterclockwise, backing arc associated with
cold advection vertical wind shear:• Indicates that the layer is becoming more stable
if the angle with the range rings increases with range. (cold advection decreasing with height)
• Indicates that the layer is becoming more unstable if the angle with the range rings decreases with range. (cold advection increasing with height)
Pre-warm Frontal 50Radar Palette Home Click Doppler
WCB Doppler Diagnosis – Diagnosis of the Eagle Wing
A
The Right Eagle Wing
•A is the radar site•BC is backing with height indicative of cold advection. •CD is veering with height indicative of warm advection•Larger angles subtended by the arcs BC and CD by the radar site A, are associated with strong thermal advections•A broad wing in the eagle is associated with strong advections
B
C
D B
C
D
A
The Left Eagle Wing
•A is the radar site•BC is veering with height indicative of warm advection. •CD is backing with height indicative of cold advection•Larger angles subtended by the arcs BC and CD by the radar site A, are associated with strong thermal advections•A broad wing in the eagle is associated with strong advections
Pre-warm Frontal 51Radar Palette Home Click Doppler
WCB Doppler Diagnosis – Diagnosis on the Gull Wing
A
The Right Eagle Wing
•A is the radar site•BC is backing with height indicative of cold advection. •CD is veering with height indicative of warm advection•Larger angles subtended by the arcs BC and CD by the radar site A, are associated with strong thermal advections•A narrow wing in the gull is associated with weak advections
B
CD B
C
DA
The Left Eagle Wing
•A is the radar site•BC is veering with height indicative of warm advection. •CD is backing with height indicative of cold advection•Larger angles subtended by the arcs BC and CD by the radar site A, are associated with strong thermal advections•A narrow wing in the gull is associated with weak advections
The Gull Conceptual Model - weaker thermal advections