Week 2 Homework Questions
1. What is evaporation? What is condensation? What is deposition? What is sublimation?
For each process, is the energy released or absorbed? 2. Describe the water cycle on Earth with regard to the movement of water into, within,
and out of the atmosphere. You should use the proper terminology as presented on the
water cycle diagram on the class web page notes. In your description, you should
specifically mention where in the cycle energy needs to be added to the water and where
energy is released by water. 3.
Temperature (°F) Saturation Mixing
Ratio (g / kg) Or Temperature (°F) Saturation Mixing
Ratio (g / kg) Or
Or Dew Point
Temperature (°F) Or Mixing Ratio (g / kg) Dew Point
Temperature (°F) Mixing Ratio (g / kg) -40 0.12 50 7.74 -30 0.21 55 9.32 -20 0.35 60 11.19 -10 0.58 65 13.38 0 0.94 70 15.95 10 1.52 75 18.94 15 1.89 80 22.43 20 2.34 85 26.48 25 2.88 90 31.16 30 3.54 95 36.56 35 4.33 100 43.22 40 5.28 105 50.30 45 6.40 110 58.90 On a day in winter 2008, the following conditions were measured on the UA campus
At 8 AM: air temperature, T = 45° F; dew point temperature = 25° F At 10 AM: air temperature, T = 60° F; dew point temperature = 25° F
At 2 PM: air temperature, T = 70° F; dew point temperature = 25° F
(a) Using the table of saturation mixing ratios provided above, compute the relative
humidity for the three times and conditions specified above. You need to show at least
one example of how you calculated relative humidity.
(b) How did the water vapor content in the air change between 8 AM and 2
PM? Explain why the relative humidity changed the way it did between 8 AM and 2 PM. 4. There are three individual questions to answer.
• •
• Explain why drops of liquid water sometimes form on the outside of a glass of ice
water. Hint. Glass is a good conductor of heat, which means that the outside of
the glass will be close to the temperature of the ice water inside, so assume it is a
few degrees above the freezing temperature of water.
What does this tell you about the dew point temperature of the air surrounding the
glass?
Does the formation of liquid drops on the outside of the glass act to warm or cool
the ice water inside the glass? Explain. Hint. Does this process add energy to or
remove energy from the surrounding environment? 5. On average, which area of the US experiences the fewest number of thunderstorms per
year? Which area of the US experiences the greatest number of thunderstorms per year? 6. What is a cloud? Briefly describe and explain, in your own words, how and why most
clouds form. If it helps you may use the concept of an air parcel in your answer. 7. Why do we bother to identify places in the atmosphere where air is forced to rise
upward? Why do rising parcels of air (parcels moving upward) cool? 8. What is the difference between a cloud droplet (suspended in a cloud) and a rain drop?
Do all clouds produce precipitation? What happens to the cloud droplets that form in
clouds that never produce precipitation? 9. Freezing rain is the name given to rain that falls when surface temperatures are below
freezing. Unlike a mixture of rain and snow, ice pellets (both of which are sometimes
called "sleet"), or hail, freezing rain is made entirely of liquid droplets (From Wikipedia).
Which skew-T below has freezing rain? And why? Hint: the red lines are the 0°C lines.
(a) (b) (c) 10. What is virga? Briefly describe the specific environmental conditions necessary for
virga to happen? Extra credit question:
11. An air parcel with a pressure of 1000 mb has a temperature of 12 C and a dewpoint of
8 C. What is its relative humidity? Hint: Use the chart from question 3.
If a different air parcel has a temperature of 20 C and a relative humidity of 70%, find its
dewpoint. The pressure of this parcel is also 1000 mb. Hint: You can still use the chart
from question 3.
