Test 1 Flashcards
What are water droplets found in temperatures below freezing referred to as?
supercooled
What are regions of a cloud transformed to ice crystals, where the cloud is saturated with respect to ice?
glaciated
True or False.
In mixed-phase clouds, the transition of supercooled liquid to ice generally takes places rapidly and tends to begin in the highest (coldest) part of the cloud, where ice is nucleated, and then work downward.
True.
Which of the following statements are true of homogeneous nucleation within clouds?
A. It takes place at relatively warm temperatures.
B. It takes place at very cold temperatures.
C. It does not requires ice forming nuclei.
D. It is vulnerable to thermal agitation, which can reduce the chances of it occurring.
E. It is the prevalent process in cloud ice nucleation.
B, C, and D
Which of the following statements are true of heterogeneous nucleation within clouds?
A. It does not require ice forming nuclei.
B. It requires ice forming nuclei.
C. It is the prevalent process in cloud ice nucleation.
D. It is the least prevalent process in cloud ice nucleation.
E. It takes place by deposition, contact, or freezing processes.
F. It takes place by freezing, sublimation, or condensation processes.
B, C, and E
True or False.
The concentration of active ice-forming nuclei in clouds increase as the cloud temperature drops.
True.
The number of active ice forming nuclei decreases with increasing relative humidity causing heterogeneous nucleation to occur more frequently in the coldest part of the cloud near the cloud top.
False.
Once an ice crystal has formed, it can grow through which of the following processes?
A. Aggregation B. Nucleation C. Sublimation D. Accretion E. Diffusion deposition F. Condensation
A, D, and E
This process occurs due to differences in the saturation vapor pressure between ice and liquid water. At a given temperature, the vapor pressure over a water surface is greater than that over an ice surface. As a result, a vapor pressure gradient develops between the droplets and crystals and water vapor moves from the higher pressure surrounding the droplets to the lower pressure surrounding the crystals, resulting in crystal growth at the droplets’ expense.
A. Aggregation B. Nucleation C. Sublimation D. Accretion E. Diffusion deposition F. Condensation
E
In the diffusion deposition ice growth process, the optimal ice crystal growth rates occur around ______ degrees C.
A. -5 B. -10 C. -15 D. -20 E. -40
C
In this ice formation process, ice crystals grow via collision with supercooled droplets. The supercooled droplet freezes on contact and sticks to the original ice crystal to form rime ice. This process is optimal in saturated layers with temperatures of 0 to -10 degrees C.
A. Aggregation B. Nucleation C. Sublimation D. Accretion E. Diffusion deposition F. Condensation
D
Graupel or snow pellets are primarily formed by which of the following processes?
A. Aggregation B. Nucleation C. Sublimation D. Accretion E. Diffusion deposition F. Condensation
D
In this process ice crystals grow through collision with each other. Liquid molecules on the outer surface of the crystals serve to increase bonding between two colliding crystals. This process is maximized at or near 0 degrees C.
A. Aggregation B. Nucleation C. Sublimation D. Accretion E. Diffusion deposition F. Condensation
A
Crystal habits that are dendritic are most favored at cloud temperatures between ___________ degrees C. If these temperatures are present in a cloud, the potential for subsequent ___________ is greatest.
-12 and -16
heavy snowfall
Observation and laboratory experiments indicate that the optimal conditions for ice crystal initiation and growth are in cloud layer that are saturated with respect to ___________ and thus supersaturated with respect to ____________, with temperatures in the __________ degrees C range.
liquid water
ice
-10 to -18
Aircraft icing potential is greatest within clouds with temperatures between ________ degrees C.
A. 0 and -15 B. -10 and -20 C. -20 and -30 D. -30 and -40 E. -40 and colder
A
In GOES 3.9 micrometer imagery, lower clouds (stratus or stratocumulus) containing water droplets appear _________, while the higher clouds (cirrus) containing ice particles appear __________.
white
dark
True or False.
In a cold layer of a sounding in a marine environment, the coldest temperature in the saturated upper cold layer is -9 degrees C. Ice crystals are not likely to exist in this layer.
False
In the surface-based cold layer in a typical wintertime precipitation scenario, the warmest portion is nearly saturated and contains T = ~+1.0 degrees C for a depth of about 200 meters. If frozen hydrometeors are entering this cold layer from above, which is the most likely phase of the precipitation?
A. Liquid
B. Freezing
C. Frozen
C
What are the 3 primary processes in the atmosphere that always directly involve latent cooling?
A. Turbulence B. Melting C. Convection D. Evaporation E. Sublimation
C, D, and E
For a cloud depth of about 800 meters, what would be the most likely precipitation type and/or rate?
A. Moderate snow
B. Drizzle or freezing drizzle
C. Moderate rain
D. Rain showers
B
What would be an appropriate rain/snow thickness (1000-500 mb) threshold for a location at 1500 m (4921 ft)?
A. A value somewhat greater than 2840 meters.
B. A value somewhat greater less than 5400 meters.
C. A value somewhat greater than 5400 meters.
D. A value somewhat less than 2840 meters.
C
What are some of the important parameters utilized by model precipitation type algorithm approaches such as Bourgouin, Baldwin, Czys, and Ramer?
A. Skin or surface temperature
B. Climatology of sounding and the associated precipitation types
C. Wet-bulb temperature profile
D. Residency time of hydrometeors in warm regions of a sounding
E. Positive (> 0 degrees C) and negative ( 0 degrees C) layers in the sounding
All
Which of the following are reasons that analyses based on surface observations alone should not be used to assess model initial conditions?
A. The spacing between the stations is irregular.
B. Similar instruments are used for different observational platforms.
C. Instruments give representative information for a model grid box.
D. Instruments have systematic observational bias.
A and D
