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60 Cards in this Set
- Front
- Back
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atmosphere composition? |
Nitrogen: Oxygen: Carbon Dioxide: Ozone: Water Vapour: |
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What aids in changing state? |
Wind, dust, smoke, salt in atmosphere because it has condensation nuclei |
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How does precipitation occur? |
Water vapour binds with minute particles like dust, smoke and salt in order to create precipitation |
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Three properties of the atmosphere? |
Mobility - air molecules move freely compression - compressed due to rise in pressure, higher temperatures Expansion- air expands, decrease in pressure and decrease in temperature |
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Where is the most weather found in and what altitude? Does the altitude vary with temperature |
Found in troposphere and 36000', yes it does and higher altitudes in the warmer areas and lower in the colder areas |
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ICAO standard |
dry gas, 29.92, 15 degrees, 1.98/1000' |
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If temperature is higher than ICAO standard what happens to TALT will it be higher or lower than Indicated |
true altitude will be higher than indicated |
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2 categories of clouds |
Stratiform - horizontal layer cumuliform - rising air content associated with updrafts and downdrafts |
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What are the 4 types of clouds of vertical development |
Cumulus, TCU, CB, ACC |
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Describe Cumulus clouds |
- detached clouds, sharp outlines - top looks like cauliflower bumpy beneath and in cloud |
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Describe tcu |
- cumulus congestus - rapid growing and very rough air |
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Describe CB |
60-70k feet (heavy, dense, indicator of a thunderstorm ) - most dangerous for pilots |
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Describe ACC |
Impending TS, turbulence, precip, icing, updrafts and downdrafts in and below clouds |
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What is the cloud coverage range beginning with SKC
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SKC - no clouds Few-2/8 or less SCT - 3/8-4/8 BKN- 5/8-7/8 OVC 8/8 |
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What is station pressure What happens to atomspheric pressure as you ascend |
column of air extending from station to top of atmosphere Atmospheric pressure decreases since less weight in terms of column of air above that point |
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What is MSL pressure |
Standarized, adding station pressure the weight of an imaginary column of air (12 hr prior observation |
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What is altimeter setting
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Pressure when set on subscale of A/C altimeter which causes instrument to indicate true height above MSL |
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What are the two types of pressure system, and the distance between 2 lines indicate how much of a pressure difference? |
High/low pressure and 4 hpa |
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What are isobars |
Lines that join areas of equal barometric pressure |
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In a high pressure does it increase or decrease in towards the center. What is another name for high pressure |
It increases towards center, known as anticyclone |
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In a low pressure does the pressure increase or decrease towards the center. What is another name for low pressure |
it decreases towards the center, known as a cyclone |
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What are bulge from lows called? What are bulge from highs called |
Troughs and ridges respectively |
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What is buy ballot's law |
In northern hemisphere if your back is to the wind the low pressure is on your left |
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How does a low rotate and how does a high rotate |
Low: rotates CCW and air rises and expands High: rotates CW sinks and clear skies |
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What is pressure gradient? |
Change of pressure with a horizontal distance |
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What happens to isobars in a steep and shallow pressure gradient |
- Isobars crowded and far apart respectively |
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What pressure does surface wx charts use |
MSL pressure |
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Define wind, how does air like to move |
horizontal pressure differences causing air to move. Air likes to move from high pressure to low pressure |
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What happens in northern hemisphere to make the airflow parallel to isobars? |
The pressure gradient and coriolis force create this effect |
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Coriolis force direction in the northern hemisphere? |
To the right |
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What does friction do to winds up to 3000' (3 things) |
- slow down - flow into low pressure areas - flow out of high pressure areas |
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What is wind shear? |
-Change in wind speed/direction in short distance -two winds in opposite direction |
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What is speed shear
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- two winds close together in same direction |
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Where can wind shear be encountered in flight? (4) |
1) lower than 3000' Frontal surfaces Jet streams Temperature inversions |
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Where can wind shear be found near ground |
1) frontal shear 2) Associated with TS 3) Temperature inversion 4) Obstructions |
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What are jet streams? What altitude are they found at IS it higher in the summer or the winter What are they associated with? What is the minimum speed for it to be considered max speeds? |
1) high wind speeds in a narrow band 2) They are found between 20000-40000' 3) Higher in the summer 4) associated with frontals 5) minimum speed is 60 knots, max is 250 knots |
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What determines amount of water vapor the air can hold
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Temperature
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Whats the transfer from Gas to liquid called? |
Condensation |
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What's the transfer from gas to solid called? |
Sublimation |
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What is relative humidity? |
Ratio of water vapour actually in air compared to max the air can hold
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What is saturation |
amount of water vapour is max possible at the existing temperature |
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If water vapour content remains the same and temperature increases or decreases what happens |
Temp increases: then RH decreases Temp decreases: RH increases |
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What is dewpoint |
temperature in which air is cooled to achieve saturation |
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What is stable air? What does it mean for pilots? |
-air that resist upward or downward displacements - low vis, fog, stratus clouds, steady precip, smooth flying |
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What is unstable air? what does it mean for pilots |
- Tends to move vertically - Good vis, vertical clouds, bumpy and gusty conditions |
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Name the lifting agents and describe them (5)? |
Convection - warm air rises as cold air subsides orographic - air forced up slope Frontal - air force to rise due to wedge of colder air (warm front) Mechanical - Friction between air and ground and terrain roughness Convergence - air converges and forced to rise |
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What is an air mass |
- large section of troposphere with relatively uniform properties and temperature horizontally |
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Maritime air mass vs continental air mass vs arctic, polar and tropical |
Maritime -> Formed over large body of water Continental - > formed over large land mass Arctic - > cold air from high latitudes Polar -> temperate air mass (30 degrees north lat) Tropical - Warm air mass from the equator area |
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North american air masses |
cA (Winter only) , mA, mP, mT |
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What are 3 main factors that determine the weather in an air mass? |
- moisture content - cooling process - stability of air |
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What are 3 cooling process that contribute to formation of clouds |
- Air in contact with relatively colder ground - Advection of warm air over cold surface - Expansion brought about by lifting agents |
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What is a front |
transition zone between 2 air mass |
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Describe a warm front and a cold front |
Warm front: rides over the cold air, retreating cold air, Shallow slope Cold front: Cold air under cuts warm air to push warm air out, Steep slope |
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What is a stationary front? |
2 air masses that are not moving |
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Severity of weather in a front 5 things |
1) Slope of front 3) Temperature of lifted air mass 4) moisture content 5) stability of lifted mass |
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What happens to the dewpoint with warm front passage, and cold front passage |
Warm front: Dew point temperature increases Cold front: Dew point temperature increases |
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Precipitation and cloud formation factors in a warm front (3) |
1) Moisture of warm air 2) Stability of over running warm air 3) Degree of over running |
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Precip and cloud formation factors in cold front (3) |
- moisture of warm air - stability of lifted warm air - degree of lift (Slope and speed) |
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Cloud and precip associated with warm air |
- Cirrus, Cs, As, AC - continuous precipitation |
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Clouds and precip associated with cold air |
- no precip, heap clouds, and showery precipitation dependent on stability of warm air |
