Weather Flashcards
What season will the jet stream be stronger?
The jet stream is stronger and more south in the winter.
What is the difference between surface charts and constant pressure charts relative to the lines shown?
The lines on a surface analysis chart are isobars (lines of constant pressure). The lines on an upper air analysis show contour lines which connect areas of equal height above mean sea level since all the chart shows the same pressure.
Does the wind parallel contour lines on a constant pressure chart?
Yes
What affects does ice have on an airplane?
It increases drag, decreases lift, and lowers the critical angle of attack
Where is ice most commonly oriented relative to a low pressure system?
North East Quadrant of a low pressure system
If you are riding in turbulence in a cloud below the freezing level, what can you expect?
An increase of turbulence is indicative of an increase in lift, which would result in us expecting an increase in ice accumulation.
What are conditions where clear ice will most likely be found?
- temps close to the freezing point with large amounts of water
- high aircraft velocities
- large droplets
What conditions where rime ice will most likely be found?
- low temperatures
- less liquid water
- low velocities
Approved anti-icing and de-icing equipment is not approved for flight into freezing rain. T/F
True
The older a cloud it, the more or less likely it is to contain ice?
less likely, because most supercooled water droplet will form into ice crystals
T/F The more lifting action, the greater liklihood of ice?
True
Describe Ram Rise Temperature increase?
The surface temperature of he aircraft increases with airspeed
What is roll upset with regards to icing?
It occurs when ice builds up aft of the protected surfaces, which can create aileron self-deflection due to negative pressure above the wing, which degrade roll handling characteristics.
How to recover from roll upset?
- lower angle of attack
- increase airspeed or extend first notch of flaps to further lower angle of attack
- level the wings if in a turn
Where is turbulence the greatest in a thunderstorm?
Usually the front side of the storm as well as the side it is being fed moisture
A storm that is moving eat, with a moist southerly flow will have most turbulence on the east and southside of the storm?
True
A thunderstorm gust front can extend how far out in front ofa strong storm?
over 15 miles in front of it
Airmass thunderstorms are caused mainly by what?
Air flowing over mountains or unequal heating of the earth
Embedded thunderstorms are most likely where?
Along the warm front or stationary frontal zones
When are convective sigmets issued?
- lines of thudnerstorms at least 60 miles long
- Area of very strong thunderstorms affecting 3,000 square miles covering at least 40% of the area
- Embedded or severe t-storms
- tornadoes
- 3/4” of greater hail at surface
- wind gusts greater than 50 knots at the surface
- indication of rapidly changing conditions
Where is the v-notch in a thunderstorm, and what does it represent?
It indicates that large particles are being swept away from the updraft by strong winds. Usually points in the direction the storm is moving
What kind of weather information can be available in a cockpit?
airborne weather radar, lightning detection systems, or uplink/downlink weather (nexrad)
What is the latency of most nexrad XM up link radar imagery?
around 5 minuts
What weather conditions are the primary reason for weather to be below ILS minimums?
Fog
When does fog normally occur, and is it possible for it to occur all day?
Usually fog occurs in the morning, but it is possible for it to last all day
What is advection fog, and when would it occur?
It occurs when cold, or snow covered ground with a low and strong temperature inversion, when warm moist air flows over the cold surface.
What season does advection fog normally occur in?
It normally occurs in the winter months when there has been a cold snap, and then warm moist air moves north from the gulf.
What is radiation fog, and when is it likely to occur?
Radiation fog “ground fog”, forms during night with calm winds and a small temperature/dewpoint spread
What does radiation fog typically do right after sunrise?
It usually thickens significantly.
What causes fog to lift, and what can be a barrier to this?
When the sun comes out, it is thought that it “burns” the fog away. When the clouds above the fog are thick and low, the sun is unable to warm the ground as much, which means the fog will not dissipate quickly
Does radiation fog get thicker or less thick lower to the ground?
Thicker
What affect does wind speed have on radiation fog?
High wind speed dissipate fog quicker, than lower wind speeds
Does a warm frontal zone cause fog, and why?
Yes, it is caused by warm rain falling thing cool air near the surface
Stronger surface winds than forecast means what?
The weather system will be stronger
In the northern hempishpere, if you put your back to the wind you left hand will point where?
To the dominating area of low pressure
In late fall/winter, or early spring, a brisk southerly winds aloft with cold surface conditions are indicative of what?
Low IFR is present below if the surface is cold, and can expect low level wind shear if the surface winds are calm or light
Surface low pressure systems and storms should track with winds are what level?
500 mb or FL180
What is the definition of light turbulence?
A/C
- momentary slight erratic changes in altitude and / or attitude
Passengers
- Occupants may feel slight strain against seat belts
- Unsecured objects may be displaced slightly
(If the tubulence is rhythmic in nature, it is considered “light chop”)
What is the definition of moderate turbulence?
A/C
- similar to light turbulence but of greater intensity with variations in indicated airspeed
Passengers
- Occupants feel definite strains against seat belts
- Unsecured objects are dislodged
(Moderate chop is defined: rapid bumps or jolts without appreciable altitude or attitude changes)
What is the definition of severe turbulence?
A/C
- Large, abrupt changes in altitude and/or attitude with large variations in indicated airspeed
Passengers
- Occupants are forced violently against the seat belts
- Unsecured objects are tossed about
What is the definition of extreme turbulence?
A/C
- Aircraft is voilently tossed about, is practically impossible to control and may cause structural damage
Besides t-storms, where can severe turbulence occur?
While and a little after fronts occlude, on the leeward side of a mountain when the wind is strong and perpendicular to the mountain range, connections have also been found with troughs aloft
What is a good mountain flying tip with regards to airways and altitudes?
Don’t fly airways where the MEA is within 4,000-6,000 feet of your airplane’s service ceiling when it is moderately windy
What is convective turbulence and when is it most likely to occur?
Present on warm days with calm or light surface winds (summer afternoons) Easy to climb out of in the east, but in the west due to mountains, it can extend up through flight levels
What is normally the ratio of the slope of warm air in front of the warm front?
1 to 100, meaning the cold air below a warm front has a ceiling of 1 mile when 100 miles north of the warm front
What is normally the ratio of the slope of warm air in front of the cold front front?
1 to 80
The boundary between the cold air and warm air in the cool sector can cause what?
turbulence (wind shear) at the point where the cold and warm air come in contact
If there is a deep trough with strong upper level winds bringing cold air over warm air, there is instability aloft, and you can expect what?
turbulence
What is the guideline to forecasting severe turbulence?
When the lateral wind speed changes more than 40 knots in a 150 mile distance, or when the vertical wind changes more than 10 knots per 1000 feet
Does maneuvering speed increase of decrease as weight decreases?
It decreases as weight decreases
What is maneuvering speed?
It is the speed where an increase in load will cause the airplane to stall before causing permanent damage
A west to east flow (or even a northwest flow) at the 18000 foot level generally is indicative of what?
Stability at the mid-altitude levels
What is a closed low aloft, and what does it indicate?
A closed low aloft, as viewed from the 500 mb chart, shows a complete circulation of a low pressure system (closed circles) and would indicate at least moderate turbulence
