Exam 2 Flashcards
When and how are constant pressure charts created?
Creates 12Z and 00Z daily using radiosonde, aircraft, and satellite observations
What is the typical height for the 300 mb chart?
30,000 feet
Lines connecting points of equal wind speed on an upper level chart are called what?
Isotachs
What is the least likely to produce precipitation?
- Development of convective cloud updrafts
- Ground level mechanical turbulence
- Ascent of moist air forced over a mountain
- Convergence of air into a low pressure region
Ground level mechanical turbulence
Isotachs are drawn on upper level charts to aid in the identification of what?
Jet streams
_____ usually occurs in association with surface low pressure centers
Rising motion
The ISA lapse rate in the troposphere is what?
2 degrees C per 1,000 feet
What environmental lapse rate is seen in an unstable air layer?
4 degrees C per 1,000 feet
Why does the tropopause provide an upper limit to most cloud tops?
The lower stratosphere is a stable layer
Solar warming of a surface during a sunny day, with no change in the moisture content of the air layer, would be expected to produce a _______ relative humidity
Reduction of relative humidity
What could destabilize a layer of air near the ground?
Mechanical turbulence which mixes the air
What force effect causes warm air to rise and cold air to sink?
Buoyancy
What can you usually expect when planning a flight in unstable air with high relative humidity?
Convective cloud
What do you call a layer of precipitating stratiform clouds that has a cloud base height of 3,000 feet?
Nimbostratus
If an observer determines that 4/8 of the sky is covered by a cloud layer how would the sky conditions be reported?
SCT
What is an important result of the release of latent heat during condensation from water vapor to cloud droplets?
Increased buoyancy
What is the primary process by which frost forms?
Vapor deposition
Supercooled cloud droplets are observed and aircraft icing occurs most frequently in what temp range?
-20 to 0 degrees Celsius
Why does rising unsaturated air cool at a rate of 3 degrees C per 1,000 feet?
Rising air uses energy to expand in a dry adiabatic process
What is the most serious consequence for fog in aviation?
Restricted visibility
A cloud that appears bright white in both visible imagery and infrared imagery is most likely what type of clouds?
Cumulonimbus or high, thick cirrus
When flying through humid air, the density altitude is slightly ______ and your aircraft performance is _____
Higher, reduced
A fibrous, wispy looking white cloud at high elevation is typically composed of what?
Ice particles
The solid contour lines drawn on a 500 mb chart are lines of equal what?
Height
What decreases as temperature increases?
Relative humidity
The vertical motion of air caused by heating of an air parcel is called what?
Convection
A state change from a solid to a gas is called what?
Sublimation
The pressure exerted by water vapor molecules in a parcel of air is called what?
Vapor pressure
What will increase in a rising parcel of air?
Relative humidity
Small particles that serve as surfaces on which cloud droplets can form are called what?
Condensation nuclei
The fog that forms along the Pacific Ocean coastal area of California is mainly what type of fog?
Advection fog
Convective precipitation areas can be best identified on radar scan images by what?
Strong reflectivity gradients across short distances
Aircraft radar reflectivity values are most likely to be underestimates of precipitation intensity because of what?
Attenuation of the radar beam signal through heavy rainfall
Geostationary satellites have an orbit which?
Matches the speed of earth rotation
Wx radar reflectivity increases strongly with what?
Precipitation particle size
Radar reflectivity is typically strongest for what?
A layer of heavy snowfall that is beginning to melt
Water vapor products from satellites provide images of what?
Mid tropospheric moisture patterns
An air layer temp lapse rate of 2.3 degrees celsius per 1,000 ft is what?
Conditionally unstable
Latent heat is released through what processes?
Condensation, freezing, deposition
The lifted index provides info on what?
Atmospheric instability
Radiosonde sounding profile data is valuable for analysis for what?
Likelihood of convective thunderstorm formation,
Vertical wind shear,
Estimated cloud ceiling
