Quiz #3 Study Guide pt. 2

Dew, frozen dew, frost (10 pts). How do these differ [Is the nighttime minimum temperature (Tmin) above or below freezing; is the dew point temperature (Td) above or below freezing; is Tmin warmer or colder than Td)? 

Cloud condensation nuclei (CCN) (5 pts). Do CCN make it harder or easier for clouds to form? Typical concentrations. Hygroscopic nuclei. Dry haze, wet haze, and fog. "Cloud in a bottle" demonstration. Clouds clean the atmosphere.

Cloud identification and classification (45 pts). Ten cloud types. Clouds are classified according to altitude and appearance; what key words are used? You should be able to identify each of the 10 cloud types from pictures (handrawn) or from a written description (eg. high altitude cloud with a filamentary appearance). How would you distinguish between Cc, Ac, and Sc or between Cs and As? What cloud type could produce a halo? Common features on thunderstorm clouds: anvil, mammatus, shelf cloud.

Sample Questions    Quiz #3: 9,17   Quiz #4: 1,4,10,EC2   Final Exam: 8,44,50

 Satellite Photographs (10 pts).  Infrared and visible photographs.  What do white and grey on these two types of photographs represent?   Thunderstorms can produce severe weather; how would a thunderstorm appear on VIS and IR photographs?  How can satellites view clouds at night?  How is it possible to see air motions in regions where there aren't any clouds?  Geostationary and low-earth orbit satellites.  Here is a sample satellite photograph question.

Sample Questions     Quiz #4: 16     Final Exam: 38

Formation of precipitation (30 pts). Approximate sizes of cloud condensation nuclei, cloud droplets, and raindrops. It is relatively easy to form cloud droplets (condensation); what about precipitation? Which of the two processes below is the most important precipitation producing process in the US?

Collision coalescence process. Produces rain in warm clouds (clouds in the tropics which contain water droplets only). Falling droplets collide (why?) and stick together. Effects of cloud thickness and updraft speed on raindrop size. Which cloud type produces the largest raindrops and the heaviest precipitation? About how large can raindrops get (why don't they get any larger)?

Ice crystal process. Structure of a cold cloud. What are supercooled water droplets? Where are they found in cold clouds? Are there more water droplets or ice crystals in the mixed phase region in a cold cloud? Are ice crystal nuclei abundant or scarce in the atmosphere? Where does precipitation begin to form in a cold cloud? Why are ice crystals able to grow while supercooled water droplets do not? Riming (accretion). Graupel. Can the ice crystal process produce rain or just frozen forms of precipitation?

Types of precipitation (30 pts). Rain, virga, snow (snowflakes), drizzle, fall streaks, sleet (ice pellets), hail, freezing rain, graupel ("soft hail" or snow pellets). What type of cloud and special cloud characteristics are needed for hail formation?

Sample Questions       Quiz #4: 6, 9, 12, 13, 15     Final Exam: 9, 40

Reviews
Mon., Apr. 1
 4-5 pm
 Haury (Anthropology) 129
Tue., Apr. 2
 4-5 pm
 Haury (Anthropology) 129