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WEF Flashcards

(46 cards)

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1
Q

Drizzle

A

Always a warm process
Must be 2000ft thick
~(-5C)

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2
Q

Showery Precipitation

A

Clouds need to be at least 8,000-10,000ft thick

Tops (-12C) - (-20C)

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3
Q

Single Freezing Levels (rain, snow, mixed)

A

Rain: >1200ft
Snow: <600ft
Mixed: 600-1200ft

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4
Q

Freezing Rain

A

Top cold layer
Thick warm layer where ice completely melts
Cold layer with supercooled droplets
Surface 0C or less

Eastern side of US
Ahead of warm front and behind cold front
Poleward side of stationary front

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5
Q

Ice Pellets

A

Cold top layer
Warm shallow layer where droplets partially melt
Cold bottom layer

Slower accumulation rate

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6
Q

Snow

A

Freezing level is cold throughout

Heaviest snow will have temperatures closest to the freezing level

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7
Q

Heaviest snow fall

A

Surface low: 0C w/ 0 to(-5C) dew point, N and downstream of Low
700mb: -6C w/ -6 to (-10C) dew point, passage of ridge snow begins
500mb: -35/-25C, heaviest snow after 500 ridge and ends after 500 trof
Vorticity: -24 to -37C

Baroclinic Deep Occluding Low: Blizzard, >40kts/<20F, >50kts/<10F, 1-2 inches lasting 20 hrs

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8
Q

Insulation/Radiation factors

A

Latitude, seasons, diurnal changes, lapse rate and inversions

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9
Q

Ways to forecast MAX temp

A

Climatology, Advection upstream, Skew T, CCL, Persistence, Numerical Guidance

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10
Q

How to forecast MIN temperature

A

Climatology, Skew T, Dew point method, Numerical Guidance

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11
Q

Cold/Heat wave setup

A

Cold: Trof to E, Ridge to W
Heat: Trof to W, Ridge to E

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12
Q

PA/DA

A

PA: the altitude which corresponds to a given standard atmospheric pressure
DA: the altitude is the altitude in the standard atmosphere characterized by known air density in the existing atmosphere. Warmer temps - less dense, colder temps - more dense (higher take off speed).

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13
Q

Fog Formation

A

Stability, cooling, moistures and light mixing

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14
Q

Fog Dissipation

A

Instability, Heating, Drying out and Increased mixing (winds)

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15
Q

Radiation Fog

A

Nocturnal event
After rain event (36hrs)
Calm winds, Cool dew points, Clear skies
Does not form over snow
If there is a lack of moisture can be ~2ft
Extremely vulnerable to conditions

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16
Q

Advection Fog

A

Cold surface/ Warm air (maritime air)
3-9kt winds, deep fog
can extend 150-250nm

Sea fog: Warm moist air over cold water. Can still exists in strong winds if water is 30-40F

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17
Q

Upslope Fog

A

Air cools adiabatically as it rises upslope at a rate of 5.3F per 1,000ft
Begins as stratus
Great Plains, Appalachians and Rockies

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18
Q

Steam Fog

A

Unstable, Cold/Warm
2-3ft thigh
Fall, early winter

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19
Q

Frontal Fog

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A

Pre-frontal: Associated with the warm front, cP air mass (warm/cold)
Post-frontal: Associated with a cold front, caused by precip, 150-200nm behind cold front, passes with 850mb frontal trof

20
Q

Ice Fog

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A

Human made
-20C
>50 latitude

21
Q

Valley Fog

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A

Increased moisture can allow fog to form @ night
Most common in early morning
Air cools as it rises up the mountain and condenses to saturation

22
Q

Advection Radiation Fog

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A

Land advection fog that stays inland and undergoes radiational nighttime cooling

23
Q

Onshore winds (fog)

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A

~3kts even coastal fog

~10 uneven (fog in headlands/convex)

24
Q

Offshore winds (fog)

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A

Lighter winds keeps fog confined to bays

With stronger winds fog gets pushed offshore (cold/warm)

25
Forecasting Fog tools
CCL | Fog formation graphic
26
Convective Turbulence
Thermally: SFC to boundary layer (10,000ft), Warm summer afternoons with clear skies and light winds. Thunderstorm induced: MOD-EXT, 10,000-15,000ft or 5,000 of freezing level
27
Mechanical Turbulence
Low-level: caused by terrain, pressure gradient or frontal shear (less likely at nighttime) High level: mountain wave turbulence. Can extend up to 70,000ft and can extended 300nm downstream. 35kts or greater, 45 perpendicular and stable layer at mountain top.
28
Clear Air Turbulence (CAT)
Not associated with turbulence or thermally induced 1. trof present and moving >20kts 2. Horizontal wind shear of >35kts/120nm 3. Wind >55kts perpendicular to CAA 4. Wind shift >75 degrees in CAA U/L ridge, SFC cyclogenesis, Confluent jets, U/L lows, Diffluent winds, shearing Trof
29
Turbulence Chart
Light - Hor (<25kt/90nm) Vert (3-5kts/1000ft) Mod - Hor (25-49kt/90nm) Vert (6-9kts/1000ft) Sev - Hor (50-89kt/90nm) Vert (10-15kts/1000ft) Ext -Hor (>90kt/90nm) Vert (>15kts/1000ft)
30
Turbulence effects on aircraft
Fixed wing: Increase speed, increase turb/ increase wt, decrease turb Rotary wing: increase speed or arc, increase turb/ wt or lift velocity, decrease turb
31
Clear icing
0 to -8C Increase WV and droplets Cumulus cloud
32
Rime icing
``` < 0C Stable stratus (0 to -15C) and cumulus (-15C) ```
33
Mixed icing
-9 to -15 cumulus | Or stratus w/ embedded convection
34
Frost
<0C surface or descending w/ increased humidity
35
Stratiform clouds (icing)
Horizontal hazard Mid-low levels 3,000-4,000 ft Time most common
36
Cumuliform clouds (icing)
Vert hazard | All types of icing
37
Trace icing
0 to -40C | 0 to -7 with DP of < 2 / -8 to -15 with DP < 3, with weak CAA
38
Light
0 to -22C 0 to -7 with DP of < 2 / -8 to -15 with DP < 3, with strong CAA Occasional use of deicing equipment
39
Moderate icing
0 to -15C | Continuous use of deicing equipment
40
Severe Icing
Deicing no longer useful | Can occur in all thunderstorms
41
Icing intensity (dew point depression)
Light: 3 to >2C Mod: 2 to 0C Severe: OC
42
Levante
Winds from NE/W through the Strait of Gibraltar Azores High over Spain 12-25kts
43
Mistral
NW/NE offshore winds A and B are Blocking ridges. C is series of depressions. 40-100kts
44
Sirocco
SE or SW winds originates over N Africa SE (cloudiness and drizzle) SW (blowing dust)
45
Bora
Cold katabatibc wind High pressure over Yugoslavia region 70-110kts
46
Gregale
Similar to Bora but central Mediterranean with NE winds

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