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Quiz 7

Why is growth by condensation not a precipitation producing process?
Once all the small droplets have combined with the larger ones, there is insufficient water vapor to grow the droplets anymore.
Describe the process of warm cloud growth for precipitation.
In this process droplets of different sizes are falling with the larger one colliding with the smaller ones and coalescing. This is the collision-coalescence process. It occurs in a cloud where the temperature is above zero degrees Celsius. Therefore, no ice crystals are present.
Describe the process of cold cloud growth for precipitation.
In this process, the Bergeron Process, ice crystals which have a lower saturation vapor pressure than does water vapor, grow at the expense of the water vapor. The cloud has water droplets that are supercooled and ice crystals present.
terminal velocity
the final speed obtained by an object falling through the atmosphere, when friction with the surrounding air balances the force of gravity
How do ice crystals grow in the cold cloud precipitation process?
What is the difference between riming and aggregation?
Riming is growth of an ice crystal as it collides with a water droplet that freezes on contact. Aggregration is the process where ice crystals come together.
In what cloud does hail form?
What is the difference between sleet and freezing rain?
The difference is the sleet is frozen before reaching the ground and freezing rain freezes on contact with a super cooled surface.
What is the common feature in the temperature profile for each of these precipitation types?
Sleet and freezing rain form in the presence of a frontal inversion.
What are ways to measure precipitation?
Air pillows for snow, rain gauges, tipping bucket gauges.
What are some of the errors associated with measuring precipitation?
Wind blown, overestimate using radar.
What is cloud seeding? How is it preformed? What precipitation formation process is involved in cloud seeding?
Cloud seeding is the process of introducing "ice" nuclei into a cloud to create precipitation. It takes place by the Bergeron process, and can only occur in cold or cool clouds.
Describe the Begeron process for precipitation formation
In the Bergeron process, the growth of cloud droplets into precipitation is accomplished through sublimation and deposition. The presence of ice crystals makes this process possible. This process occurs in a cold and cool cloud.
Describe the Collision-Coalescence process for precipitation formation
For collision and coalescence, this process occurs without ice crystals. Cloud droplets fall at different rates and some water droplets will grow larger while some get pushed away.
How do collision and coalescence increase the size of cloud droplets?
Cloud droplets initially grow by condensation. The different fall speeds of cloud droplets in this process makes it possible for cloud droplets to grow by colliding and coalescing. Cloud droplets of like size will not come together because the terminal velocity is the same.
It is never too cold to snow
What types of materials are used in cloud seeding?
we can use frozen carbon dioxide or silver iodide
Explain the process of lake-effect snow
In lake effect snow, cold dry air moves across the Great Lakes. Orographic lift causes the moistened air to rise. This results in precipitation on the leeward side of the lakes in the areas of enhanced lift
What determines the terminal velocity of falling droplets and raindrops?
This is determined by the size of the droplets and raindrops.
Can it be too cold for the formation of sleet?
Extensively rimed ice crystals
found in Cumulonimbus clouds