Metr 10: Activity 4
Due: Tuesday, October 2nd, 2018 (at 11:59 P.M.)
Submit electronically via Canvas (.doc, .docx, or .pdf file format).
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Please answer all questions in complete sentences. Show your work for #4.
Each question is worth 1 point (15 points total for this activity).
1. What is a cloud-condensation nuclei (CCN)? Why are they so important in the atmosphere? Give three examples of CCN.
2. In a volume of air, how is the actual vapor pressure different from the saturation vapor pressure? When are they equal?
3. What variable does saturation vapor pressure primarily depend upon?
4. The vapor pressure of air is 10 millibars, and its saturation vapor pressure is 25 millibars. Calculate the relative humidity (RH) of the air.
5. Give two instruments that can be used to measure humidity, and explain how each works.
6. What is the definition of dew-point temperature? As it increases, what happens to the amount of water vapor in the air?
7. How is the separation between dew point and air temperature related to relative humidity of air?
8. Why do hot and humid summer days usually feel hotter than hot and dry summer days?
9. It is a hot and muggy summer afternoon in New Orleans (pronounced by some Southerners as “NAH-LINS”). The air temperature is 90°F, and the dew point temperature is 75°F. Using the table in Lecture 5, calculate the heat index.
10. The air temperature at night cools to the dew point temperature in a deep layer, producing fog. Before the fog formed, the air temperature cooled by 3°F each hour. After the fog formed, the air temperature cooled by only 1°F each hour. Give two reasons why the air cooled more slowly after the fog formed.
11. Name the four major categories of clouds, and give their respective Latin roots.
12. You observe rain and an overcast sky. Give at least two different ways you could determine if the cloud above you is a nimbostratus or a cumulonimbus.
13. Take two pictures, each with a different cloud type. Almost everyone these days has a smart phone with a built-in camera. Attach the pictures below. For each cloud, give its name, and explain how you know this.
14. How does radiation fog form?
15. How does advection fog form?
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