2_2 Flashcards
You have determined that the alternate weather minimum for CYQY at your ETA, 1300Z, is 400-1. Using the following TAF, can you use CYQY as your alternate?
TAF CYQY 111034Z 1111/1123 22008KT 3SM -DZ BKN008 OVC025 TEMPO 1611/1612 2SM +RA OVC010 FM161300 30015KT -SHRA 1SM BKN005 BECMG 1613/1617 1/2SM OVC005 FM161800 30020G30KT 2SM +TSRA OVC008 PROB30 1619/1620 1/4SM OVC001RMK NXT FCST BY 162000Z=
No
Explanation
AIM, RAC 3.13: Aerodrome forecasts (TAF) that contain the terms BECMG, TEMPO or PROB may be used to determine the weather suitability of an aerodrome as an alternate, provided that:
- where conditions are forecast to improve, the forecast BECMG condition shall be considered to be applicable as of the end of the BECMG time period, and these conditions shall not be below the published alternate minima requirements for that aerodrome;
- where conditions are forecast to deteriorate, the forecast BECMG condition shall be considered to be applicable as of the start of the BECMG time period, and these conditions shall not be below the published alternate minima requirements for that aerodrome;
- the forecast TEMPO condition shall not be below the published alternate minima requirements for that aerodrome; and
- the forecast PROB condition shall not be below the appropriate landing minima for that aerodrome.
Question 02
TAFCYUL 061438Z 0615/0717 14006KT P6SM SCT060 BKN170 BECMG 0616/0618 16012KT FM062300 16012G22KT P6SM BKN040 OVC100 FM070100 17012G22KT P6SM -RA OVC030 FM070500 18012G22KT 5SM -RA BR OVC020 FM071000 25015G25KT P6SM -SHRA SCT020 BKN030 OVC120 RMK NXT FCST BY 061800Z=
The above TAF was issued at ____ and is valid for _____
1438Z; 26 hours and 22 minutes
AIM, MET 7.4
TAF AMD CWWU 151937Z 1519/1618 26012KT 6SM BR OVC004 TEMPO 1519/1603 2SM SHRA BR OVC003 BECMG 1523/1601 26015G25KT FM160300 28015G25KT P6SM FEW008 BKN012 FM160600 28010G20KT P6SM SCT008 FM161200 36015KT P6SM FEW012 BECMG 1614/1616 36012G22KT RMK NXT FCST BY 160000Z=
According to the TAF above, how will the winds change at CWWU after the passage of the cold front?
They will blow from the north-west instead of blowing from the south-west.
Explanation
The surface wind always veers when a front passes. When flying through a cold front, you can expect to have wind shifts and gusts. It usually occurs close to the frontal surface.
AIM, MET 7.0: See explanations.
FBCN35 CWAO 100330 YQB
DATA BASED ON 100000Z
VALID 110000Z FOR USE 1800-0600Z
3000 6000 9000 12000 18000
2610 238-01 287-08 268-14 2627-25
According to these upper level wind and temperature forecasts, what are the winds and temperatures expected in Quebec (YQB) at 9,000 feet?
280ºT at 7kts, -8ºC
Explanation
AIM, MET 9.2: Upper level wind and temperature forecasts (FDs) are upper level forecasts of wind velocity, expressed in knots and to the nearest 10s true, and temperature, expressed in degrees Celsius. Temperatures are not forecast for 3 000 ft; in addition, this level is omitted if the terrain elevation is greater than 1 500 ft. All forecast temperatures for altitudes over 24 000 ft are negative.
Forecasts in digital form of the winds and the temperatures aloft (FB) are currently available over the phone. They have a similar format to FD forecasts but are updated four times a day and include other improvements. FD forecasts will continue to be available but will gradually be replaced by FB forecasts.
SIGMETs are issued by:
Meteorological watch offices.
Explanation
AIM, MET 6.1: Information message issued by a meteorological watch office (MWO) to advise pilots of the occurrence or expected occurrence of specified weather phenomena, which may affect the safety of aircraft operations, and the development of those phenomena in time and space.
Which of the following is true regarding the SIGMET below?
WCCN34 CWUL 161526
SIGMET A3 VALID 161525/161925 CWUL-
WTN 115 NM OF 4430N05624W. TC MARIA OBS AT 1500Z. CB TOP 420 WTN 115NM OF CNTR. TC MOVG NEWD AT 45KT. FCST 1740Z TC CNTR 4648N5430W. WKNG. END/GFA34/CMAC-E/MF
Tropical Cyclone Maria is forecast to weaken from 1740Z.
AIM, MET 6.0: See the explanations.
Refer to Image 2 in the Appendix.
On a weather chart, this symbol represents:
Intermittent snow.
AIM, MET4.0: See the explanations.
On a surface weather map, winds at 2,000 feet AGL blow ______ to the isobars, and on an upper level analysis charts, wind blows ______ to the contours.
Parallel; paralell
Explanation
AIM, MET 10.0:4. The winds at 2000 feet AGL blow roughly parallel to the isobars - in a clockwise direction around Highs and counter-clockwise around Lows. Wind speeds vary with the distance between isobars. Where the lines are close together, one can expect moderate to strong winds; where they are far apart, expect light variable winds.
AIM, MET 11.1: (c) Wind Direction: Wind direction may be determined at any point by using the height contours. The wind generally blows parallel to the contours and the direction is determined by keeping the “wind at your back with low heights to the left”. The plotted wind arrows also provide the actual wind direction at the stations.
On upper-level analysis charts, temperature is analyzed and indicated with dashed lines drawn at 5°C intervals on:
850 and 700 hPa charts only.
AIM, MET 11.1: (b) Temperature: Temperature is analysed on the 850 and 700 hPa charts only. Dashed lines are drawn at 5°C intervals and are labelled 5, 0, -5, etc. Temperatures at 500 and 250 hPa are obtained by reading the number in the upper left corner of each of the station plots.
Meteorological parameters of 250 hPa charts are measured _____ , and the charts are issued ____
Twice a day at 0000Z and 1200Z; about three hours after the data is recorded.
Explanation
AIM, MET 11.1: Meteorological parameters in the upper atmosphere are measured twice a day (0000Z and 1200Z). The data are plotted and analysed on constant pressure level charts. These charts always indicate past conditions.
The 850 hPa (5 000 ft) 700 hPa (10 000 ft) 500 hPa (18 000 ft) 250 hPa (34 000 ft)
analyzed charts are available in Canada and are generally in weather offices about three hours after the data are recorded.
When using ANAL in conjunction with surface analysis charts, it is possible to have a good idea of the current weather and weather system scope.
What is the approximate pressure at 18,000 feet?
500 mbar.
AIM, MET 3.3: Upper Level Chare - ANAL are prepared for following levels:
850 hPa (1 500 m/5000 ft)
700 hPa (3 000 m/ 10 000 ft)
500 hPa (5 500 m/ 18 000 ft)
250 h Pa (10 400 m / 34 000 ft)
1 hectopascal = 1 millibar
Refer to Image 1 in the Appendix.
In the red box of this upper-level wind and temperature chart, the wind is from the _____ at 53 knots and the temperature is _____
295°T; ISA - 12°C.
Explanation
AIM, MET 11.2: Upper level wind and temperature charts are issued by the world area forecast centre (WAFC), through the U.S. National Oceanic and Atmospheric Administration’s (NOAA) National Weather Service (NWS) in Washington, D.C. Winds are depicted for FL240, FL340, FL390 and FL450 using arrow shafts with pennants (50 kt each), full feathers (10 kt each) and half feathers (5 kt each). The orientation of the shaft indicates wind direction (degree true).
Temperatures (°C) are presented in bold type at Fixed grid points for the flight level. All temperatures are negative unless otherwise noted.
In North America. ICAO standard atmosphere is based on average winter and summer at 40° latitude. Here are the conditions:
- air is a dry gas;
- pressure at mean sea level is 29.92 inches of mercury;
- temperature at mean sea level is 15°C;
- temperature decreasing rate with altitude is 1.98°C for every 1,000 feet.
On Significant Weather Prognostic High-Level Charts (SIGWX HI LVL), what is the meaning of “OCNL embedded CB”?
Well-separated embedded CBs (50-75% inclusive)
Explanation
AIM, MET 12.2: (a) Active thunderstorms: the cumulonimbus (CB) symbol is used when thunderstorms occur, or are forecast to occur, over a widespread area, along a line, embedded in other cloud layers, or when concealed by a hazard.
The amounts and the spatial coverage (in brackets) are indicated as:
ISOL (isolated) - for individual CBs (less than 50%)
OCNL (occasional) - for well-separated CBs (50-75% inclusive)
FRQ (frequent) - for CBs with little or no separation (greater than 75%)
NOTE: The definitions of the above terms, as used in ICAO charts, differ from those used for national SIGMET, AIRMET and GFA. The ICAO definitions involve 25% greater coverage in all cases. Some charts may include SCT which refers to 25-50% areal coverage. In addition, ISOL is used by ICAO while ISOLD is used in national forecasts.
Embedded CBs may or may not be protruding from the cloud or haze layer. The following abbreviations are used to indicate the presence of CBs: ISOL embedded CB,
OCNL embedded CB, FRQ embedded CB and FRQ CB. All other clouds are depicted using OKTA amounts, followed by the cloud type. In certain cases the abbreviation LYR
(layer or layered) is used to indicate cloud structure.
For this series of 5 questions, refer to Image 4 in the Appendix. When was this chart issued?
Was issued on July 21, 2015, at 1800Z and is valid from July 22, 2015, at0600Z.
Explanation
AIM, MET 3.1
The longer jet stream (north of Europe):
Has its core located at the FL330.
Explanation
AIM, MET 12.2: See explanations.
What is the symbol “XXX” on a SIG prog chart?
A level below of the level of the chart
What is the lowest level of the tropopause on this SIGW prog chart?
FL 230
AIM, MET 12.2
What is the altitude of the lowest cumulonimbus cloud base on this chart?
Impossible to determine.
On Significant Weather Prognostic Charts, fronts and pressure centres are representative of:
Their surface position for the validity period of the chart.
Explanation
AIM, MET 12.1: The CMC issues a series of significant weather prognostic charts for lower levels, from 700 to 400 hPa (FL100 to FL240). They use the same criteria as above plus the following:
- moderate to severe icing;
- cloud layers of significance;
- marked mountain waves;
- freezing level line (0°C) at 5 000-ft intervals, and labeled in hundreds of ft; and/or
- surface positions and direction of motion (in kt) of highs, lows, and other significant features (front, trough).
According to Environment and Climate Change Canada’s weather radars:
- Present a display of precipitation within 150NM of the facility site
- Storms of considerable height and intensity can be seen at greater ranges.
- These radars cannot detect turbulence.
- Radar images are updated approximately every 10 min for individual radars
- Upgrades coming
_____ is a toxic pale blue gas, almost colourless, that intercepts most of the UV radiation from the Sun.
Ozone
Explanation
At ambient temperature, ozone is a pale blue gas, almost colourless, recognizable by its bleach solution odour. It is toxic and causes coughing if breathed at high amounts. This gas is present in low quantities throughout Earth”s atmosphere: in the stratosphere, it forms the ozone layer (between 13 and 40 km of height) that intercepts most of the ultraviolet radiation (UV) from the sun (more than 97%).
Most weather phenomena occur in the:
Troposphere.
Explanation
The troposphere is the atmosphere”s first layer. Its top can be from 28,000 feet ASL at the poles to 54,000 feet ASL at the equator. In the troposphere, pressure, density and temperature decrease quickly with altitude. Most weather phenomenons occur in the troposphere, and it is the place of most of light aviation.
The troposphere top is called “tropopause.” At the tropopause, the temperature stops decreasing and is constant at about -56°C.
In the atmosphere’s lower levels, while flying towards an anticyclone centre that has a high pressure gradient, you should expect the barometric pressure to ____ and _____ winds.
Increase; strong.
Explanation
High pressure, also called anticyclone, is an area where pressure is relatively high (higher than surrounding areas).
The speed at which the air is moving from point A to point B depends on the pressure gradient. The pressure gradient, defined as the pressure variation rate for a given distance, is measured relative to the isobars.
When the isobars are far from each other, the air moving (wind) is light. When the isobars are close together, the gradient is strong and so is the wind.
You are flying at an altitude of 9,000 feet on track 090. You experience a strong drift to the north. Therefore, the low-pressure area is ______ and your true
altitude will ____________.
West; increase.
Explanation
In che Northern Hemisphere, wind blows counterclockwise around the depression and moves away from the high pressure deviating to the right (clockwise). The opposite occurs in the Southern Hemisphere.
To find che low-pressure zone, stand with the wind at your back: it will be on your left (see Buys Ballot’s law).
If you are experiencing a drift to the left, it means you are moving away from the low pressure or you are approaching a high pressure. Your altimeter will underestimate altitude.
From a high-pressure to a low-pressure area, the altitude indicated (not corrected) is higher than actual altitude. The same occurs when the altimeter passes from a warm air mass to a cold air mass.
During the process, no transfer of heat or matter is made between the parcel of rising air and its surroundings.
Adiabatic.
Explanation
As air rises, it encounters a lower pressure: it expands and cools. This process is called “adiabatic cooling.”
During the adiabatic process, no transfer of heat or matter is made between the parcel of rising air and the surrounding environment.
What is the consequence of differential heating of the Earth’s surface?
Convection.
Explanation
When air is over a warm surface, it becomes turbulent and rises fast through the atmosphere. This upward movement is called “convection.” A descending cold air current is created to replace warm air. A vertical flow appears and spreads heat through upper layers.
Think of the air that moves a small noria with a candle
Consider a parcel of air that rises from the ground where the temperature is 35°C. If the cloud base is at 8,000 feet, then the temperature at 15,000 feet will be °C.
0.5
The saturated adiabatic lapse rate is 1.5°C for every 1,000 feet.
The dry adiabatic lapse rate is 3°C for every 1,000 feet.
The dew point decreases by 0.5°C for every 1,000 feet.
In this case, consider the dry adiabatic lapse rate up to 8,000 feet. The temperature at 8,000 feet will be: 35 - [(8,000 - 0) / 1.000] x 3 = 11 °C
Now take the saturated adiabatic lapse rate between 8,000 feet and 15,000 feet. The temperature at 15,000 feet will be: 11 - [(15,000 - 8,000) / 1,000] x 1.5 = 0.5°C
The amount of water vapour that can be contained in a volume of air is determined by:
Temperature.
Explanation
Temperature governs the amount of water vapour that a given volume of air can contain. Warm air can contain more water vapour than cold air. When an air volume reaches the maximum quantity of water vapour it can bear, it is saturated.
On what do bases of vertical development clouds depend?
The difference between che temperature and the dew point.
The smaller the difference between temperature and dew point, che lower the cloud development.
Stable air regions are usually characterized by:
Poor visibility.
Explanation
In stable air, there is less or no turbulence, flight conditions are comfortable and you encounter stratus clouds. Wind and precipitation are continuous. Visibility in lower levels is quite bad and you may encounter fog.
Subsidence dries out the air by
Adiabatic compression.
Explanation
The subsidence causes an increase of the ground level atmospheric pressure and, by adiabatic compression, warms up and dries out the air going down, stabilizing the atmosphere by creating a temperature inversion. The result is a dissipation of clouds from the top and a clear sky.
Stratus clouds at a warm front indicate that the _____ air is moist and _____
Warm; stable.
Explanation
Meteorological conditions at frontal systems are predicted according to the warm air mass features.
At a warm front, if warm air is moist and stable, stratus clouds will be what you encounter. If warm air is moist and unstable, you can expect to encounter convective clouds, sometimes hidden in stratus clouds. Therefore, you should expect strong showers in front of the frontal surface.
At a cold front, if warm air is stable, you will encounter stratus clouds. If warm air is unstable, you will encounter cumulus clouds. Here, the lifting agent is the frontal surface, so the vertical development force will depend on the front’s slope and speed.
