Meteorology Flashcards
MI
Shallow
BC
Patches
PR
Partial
DR
Drifting
BL
Blowing
SH
Showers
TS
Thunderstorm
FZ
Freezing
VC
In the Vicinity
DZ
Drizzle
RA
Rain
SN
Snow
SG
Snow Grains
IC
Ice Crystals
PL
Ice Pellets
GR
Hail
GS
Snow Pellets
UP
Unknown Precipitation
BR
Mist
(If vis is equal to or greater than ⅝ statute mile. Less than that it’s Fog “Fogless”)
FG
Fog
Less than ⅝ statute mile visibility, otherwise it’s Mist. “Fogless”
FU
Smoke
DU
Dust
SA
Sand
HZ
Haze
VA (weather)
Volcanic Ash
PO
Dust/Sand Whirls
SQ
Squalls
FC
Funnel Cloud
+FC
Tornado or Waterspout
SS
Sandstorm
DS
Dust Storm
As a warm front passes, the wind will
Veer
- The ICAO Standard Adiabatic Lapse Rate
1.98ºC per 1,000 feet.
- The Saturated Adiabatic Lapse Rate
1.5ºC per 1,000 feet.
- The Dry Adiabatic Lapse Rate
3ºC per 1,000 feet.
Advection fog
Advection fog occurs when a warm, moist air mass flows across a colder surface. Also, wind is required, “windvection!”
Steam fog or sea smoke
Occurs when evaporation takes place into cold, dry air lying over warmer water
Radiation fog
On a cloudless night, especially within a high pressure system, the land surface loses heat to the atmosphere by radiation and cools. Moist air in contact with cooling surface also cools and when the temperature falls below the dew point for that air, fog forms. On clear nights, with relatively little to no wind present, radiation fog may develop. Usually, it forms in low-lying areas like mountain valleys
Conditions associated with stable air
- poor visibility
- stratus cloud formations
- steady winds
- steady precipitation
- very little or no turbulence
(STABLE POO-STSTST-NOTURD)
Conditions associated with unstable air
- good visibility
- cumulus cloud formations
- gusty winds
- precipitation
- turbulent conditions
(UNSTABLE
Characteristics typically found at a cold front
- unstable air
- cumulus cloud formations
- precipitation
- gusty winds
- good visibility
The intensity of the weather at a cold front will depend on the stability of the air, the moisture content, and the speed of the advancing cold front.
(COLD IS UNLIKE A STABLE)
How might the weather change as a warm front passes?
- The visibility will remain poor for a period of time.
- Atmospheric Pressure will decrease as the warm front approaches and will increase slowly as the warm front passes.
- A slow rise in temperature will come as the warm front approaches.
- The wind tends to veer with the passing of a warm front.
Wind and Advection
Windvection! Wind is needed for Advection
Standard Pressure in hectopascals, lb/sqin, and Hg
1013.2 mb (hPa)
14.7lb/in2
29.92 Hg
How high are Cirro/Cirrus Clouds?
20,000ft+
How high are “Low” clouds?
0 - 6,500ft
How high are “Middle”/Alto clouds?
6,500 - 23,000ft
GFA: ISOLD
Isolated clouds 25% or less
GFA: OCNL
Occasional Cloud 26% - 50%
GFA: FRQ
Frequent Clouds Greater than 50%
GFA: CAT Symbol
Clear Air Turbulence
FD 75006-37
Subtract 50, e.g, 250 Degrees True at 106kts, at negative 37 degrees Celcius
FD Wind Speed of 199
Means wind is more than 199kts
FD 269746
260 True at 97kts, NEGATIVE 46 degrees Celcius
How do you calculate cloud bases?
In AGL: Take the dewpoint spread, and divide by 2.5 degrees. Multiply by 1000ft.
In ASL: Add the station elevation to the above.
What is the dew point decrease rate?
0.5 degrees per 1000 feet
Surface Temp 15°
Surface Dew Point 5°
Find:
Height of Cloud Bases
Dew Point at Cloud Bases
Freezing Level
Height of Cloud Bases
2° Standard Adiabatic - 0.5° Dew Point Decrease per 100ft = 1.5°. 2.5°/10° spread = 4,000ft.
Dew Point at Cloud Bases
5° - (0.5°x4) = 3°.
Freezing Level
3°/1.5° Saturated Adiabatic - 2*1000ft = 2000 + 4000ft = 6000ft AGL. Add station elevation for ASL.
Name the Octas:
Clear
Few
Scattered
Broken
Overcast
Clear
Few 2 (less than 1/8 to 2/8)
Scattered 3-4
Broken 5-7
Overcast
Buys Ballot’s Law
If you stand with your back to the wind, the lower pressure area will be on your left side. In the southern hemisphere, the reverse is the case.
The change group “Probability” (PROB) indicates:
The 30 or 40% probability of certain weather conditions.
In order for a TAF to be issued a minimum of ____ METARs must be recorded.
2
(2 observations are needed to establish a trend)
UACN10/01
PIREP/URGENT PIREP
WA, as in WACN23
AIRMET
CN Canadian Airspace
FIR 23 is Winnipeg flight information region
WS
as in WSCN23
WS Is a Sigmet
CN Canadian Airspace
FIR 23 (Winnipeg flight information region)
LCL
PATCHY
XTNSV
Non-convective GFA weather
LCL 25% or less
PATCHY >25% to 50%
XTNSV >50%
QS on a GFA
Quasi-Stationary Front, less than 5kts
Broken or overcast organized clouds
Continuous freezing precipitation
Intermittent freezing precipitation
Moderate icing
Severe icing
Moderate low-level turbulence
Severe low level turbulence
Moderate high level turbulence
Severe high level turbulence
What’s steeper, a warm front or cold?
A cold front, which is why cold fronts usually feature a narrow band of bad weather, isolated along the front. After the approach of a cold front the weather gets remarkably better.
Warm fronts are much shallower in slope, which is why the cloud formations are much more stratus.
CAVOK
(cloud and visibility OK) when the following conditions exist simultaneously:
Visibility is 10km or more. No CB or TCU and no cloud below 5000 feet or Minimum Sector Altitude (MSA) (whichever is the greater). 6SM vis or more.
The maximum period of validity for a TAF is…
30 hours
What is one of the most easily recognized discontinuities across a front?
Temperature (and therefore you should adjust your altimiter)
Gust vs Squall
A gust is rapid and irregular
A squall is of longer duration
Supercooled water droplets are often found in abundance in clouds at temperatures between…
0ºC and -15ºC.
The diurnal change of surface wind velocity is such that during the day the surface wind
will usually
veer and increase in speed.
The forecast surface wind will be included in a GFA if it has a sustained speed of at least
. . . . . kt.
20kts
The diurnal change of surface wind velocity is such that during the day the surface wind
will usually
veer and increase in speed.
The presence of vertical air currents caused by terrestrial radiation is called…
convective turbulence.
As a cold front approaches and then passes, the air pressure will…
decrease as the cold front approaches and increase as it passes.
When a mass of cold air overtakes a mass of warm air, the cold air being more dense stays on the surface and undercuts the warm air violently. As a result, the slope is quite steep making a relatively narrow band of cloud cover of 50 nautical miles. A sharp fall in temperature, a rise in pressure and a rapid clearing usually occur with the passage of the cold front.
Snow, then ice pellets =
Death. (Freezing Rain)
TAFs are an aerodrome forecast which is intended to cover…
a five mile radius from the centre of the aerodrome issuing the TAF.
How far beyond a thunderstorm can severe turbulence occur?
Typically 20 nautical miles
