All About Weather Flashcards
What causes wind?
Pressure Gradient Force, Uneven Heating of Earth’s Surface/Temperature Differences, and the Coriolis Effect
Pressure difference cause it high pressure air to flow towards low pressure air.
This is known as the Pressure Gradient Force, it can be seen on weather maps through the spacing of Isobars (closer = high pressure = more wind/faster wind)
Temperature differences create areas of High and Low Pressures.
Coriolis Effect causes the wind to deflect to the right in the Northern Hemisphere and to the left in the Southern Hemisphere. creates wind currents
When is wind unsafe?
TailWinds: longer takeoff roll and increase in ground roll, smaller climb gradient
WindShear: Sudden Increase or Decrease in aircraft speed and altitude
CrossWinds: drift off centerline
Gusts: unpredictable wind, can cause sudden movements and gain/loss of lift
Wind Shear
Dangerous unpredictable wind that can cause major unprompted changes in airspeed or altitude.
Found:
Thunderstorms
Fronts
Temperature Inversions
Surface Obstructions (mountains)
How are clouds formed?
When water vapor condenses, this happened as air cools and reaches the dew point.
Dew Point= when air reaches 100% relative humidity
What clouds are associated with smooth vs turbulent conditions?
Cumulus/Cumulonimbus Clouds: Turbulence
Stratus Clouds: Smooth
What are some indicators of Turbulence?
1) Strong Wind Over Mountains
2) Dark Terrain on Hot Day (Thermals)
3) Rapidly Changing Wind Direction and Speed
4) PIREPS with warnings about Turbulence
5) Strong Surface Winds with Obstructions Nearby
6) Frontal Passage
7) Temperature Inversion (at the boundary between the inversion layer, and the surrounding atmosphere)
8) Jagged Clouds with Rolling Edges
9) Weather Reports
10) Large Rising Fluffy Clouds (Cumulus)
Procedures for Turbulence
1) Slow Down (stay within operation range)
2) Hold Winds Level
3) Maintain Altitude
4) Change Altitude (If possible)
5) Avoid Jerky Movements
6) Contact ATC
Microbursts
A localized powerful downdraft of air within a thunderstorm, typically less than 2.5 miles and lasts 2-5 minutes, can cause a 6,000ft descent per minute, can get up to 150mph.
How to Avoid Thunderstorms?
a. Thunderstorm Avoidance. Never regard any thunderstorm lightly, even when radar observers report the echoes are of light intensity. Avoiding thunderstorms is the best policy. Following are some dos and don’ts of thunderstorm avoidance:
(1) Don’t land or takeoff in the face of an approaching thunderstorm. A sudden gust front of low-level turbulence could cause loss of control.
(2) Don’t attempt to fly under a thunderstorm even if you can see through to the other side. (Microburst Avoidance!!) Turbulence and wind shear under the storm could be hazardous.
(3) Don’t attempt to fly under the anvil of a thunderstorm. There is a potential for severe and extreme clear air turbulence.
(4) Don’t fly without airborne radar into a cloud mass containing scattered embedded thunderstorms. Scattered thunderstorms not embedded usually can be visually circumnavigated.
(5) Don’t trust the visual appearance to be a reliable indicator of the turbulence inside a thunderstorm.
(6) Don’t assume that ATC will offer radar navigation guidance or deviations around thunderstorms.
(7) Don’t use data-linked weather next generation weather radar (NEXRAD) mosaic imagery as the sole means for negotiating a path through a thunderstorm area (tactical maneuvering).
STAY AT LEAST 20 MILES AWAY FROM THUNDERSTORMS!!!
What does atmospheric stability have to do with weather?
Stability depends on the atmospheres ability to reduce vertical motion.
In an Unstable Atmosphere, small vertical movements tend to become larger leading to turbulent airflow and convection (bad weather)
What are the three different types of icing?
Clear, Mixed and Rime
Clear: heavy coating of glassy ice (forms when flying in areas with high concentrations of large supercooled droplets (forms quickly)) Most Dangerous!!!
Mixed: a mixture of the two and can look opaque (accumulates rapidly and is hard to remove)
Rime: opaque or milky white deposits of ice that form when flying through stratus clouds Least Hazardous
Can you fly into known icing conditions?
NO NO NO!!!
If you encounter ice, be prepared to change altitude or route, and use deicing equipment.
Which is the defroster and the pitot heat.
What are the two conditions for ice to develop on an aircraft?
1) the aircraft must be flying through visible moisture such as a rain cloud or cloud droplets
2) the temperature at the point where the moisture strikes the aircraft must be 0* C or colder.
How can you Avoid flying into icing conditions?
By getting an accurate weather briefing.
By observing PIREPS about weather conditions in the area of flight
Observing freezing levels
Monitoring Temperature vs Dew Point Spread
Avoiding Clouds on Days with temps below freezing.
Situational Awareness in Flight
Types of Fog
Fog forms when
*air is cooled to the dew-point (temp decreases)
*moisture is added to the air (dew point increase)
Radiation Fog: clear calm nights (when the ground cools)
Advection Fog: coastal areas (moist air moves over cooler ground or water)
Upslope Fog: air that raises above the mountain
Steam Fog: sea smoke, cold dry air moves over warm water
Precipitation Fog: as warm air falls through cool air, the rain saturates the cool air
Ice fog: frozen fog, (when droplets of water are supercooled in the air)
Hazards Associated with Fog or Mist
You cannot see/ lost of visual references and can become easily disoriented
How does Frost affect aerodynamics?
Changes the camber of the wing, causing the plane to reduce its capabilities of lift and its maneuverable capabilities.
It is heavier, increasing stall speed and increasing takeoff speed.
Increase drag, by disrupting airflow.
