METR 104: Our Dynamic Weather (Lecture w/Lab) Pre-class Quiz #6: for on-Line Reading #6 Dr. Dave Dempsey Dept. of Geosciences SFSU, Spring 2012

This is a "preview" version of Pre-class Quiz #6, which is based on on-line Reading Assignment #6 plus a related diagram attached to the quiz. The "preview" version is suitable for printing and leisurely inspection before you submit your answers to the the interactive or "live" version—that is, the real thing. When you feel ready to submit your answers, go to iLearn's METR 104 "Pre-class Quizzes" section, select the interactive version, and follow its instructions.

Responses must be submitted by 12:05 p.m. Friday, May 11. I recommend that students in the Wednesday lab submit before the Wednesday lab session. (If you leave the interactive version before submitting your answers, you can save answers already entered by clicking on the "Save without submitting" button at the bottom of the quiz page, and you can return later. In any case, be sure to submit your responses by the deadline by clicking on the "Submit all and finish" button at the bottom of the quiz page.)

You will have two chances to get each question correct. (If you want to resubmit your answers, you will have to wait at least 10 minutes after the first submission.)

The Questions:

(1) Multiple Choice. Condensation and Energy Transformation. The process in which water vapor changes phase to become liquid water is called condensation. What transformation of energy from one form to another occurs when water vapor condenses? (Select the one correct answer.)

1. Radiative energy is converted into heat.
2. Heat is converted into radiative energy.
3. Heat in the water vapor is converted into latent heat in the condensed liquid water.
4. Latent heat in the water vapor is converted into heat in the air.

(2) Multiple Choice: Dew Point Temperature. What determines an air parcel's dew-point temperature? (Choose the one [best] correct answer.)

1. The parcel's temperature.
2. The parcel's pressure.
3. The water vapor content of the parcel.
4. The parcel's direction and speed of motion.

(3) Multiple Choice. Effect of Temperature on Water Vapor Saturation. There is an upper limit on the amount of water vapor that can be present in the air. When that limit is reached, we say that the air is saturated with water vapor because the air can't "hold" any more.

What determines the maximum amount of much water vapor that air can "hold"? (Select the one [best] correct answer.)

1. The amount of water vapor actually present in the air.
2. The temperature of the air.
3. The air pressure.
4. The dew point temperature.

(4) Multiple Choice. Relative Humidity. Humidity is a broad term referring to the amount of water vapor in the air. A particular, more specific measure of humidity is relative humidity. How is relative humidity defined? (Select the one correct answer.)

1. The amount of water vapor in the air.
2. The amount of water vapor in the air relative to (that is, expressed as a fraction or percentage of) the amount of other gases in the air.
3. The amount of water vapor in the air relative to (that is, expressed as a fraction or percentage of) the amount of water vapor needed to saturate the air.
4. The amount of water vapor in the air relative to (that is, expressed as a fraction or percentage of) the dew point temperature.

(5) Multiple Choice. Relative Humidity: Dependence on Temperature. What happens to the relative humidity when air warms up (for example, inside a heated house or apartment on a cold winter day)?

(Assume that the actual amount of water vapor present in the air does not change by, say, evaporation of liquid water into it.) (Select the one correct answer.)

1. The relative humidity goes up.
2. The relative humdity doesn't change.
3. The relative humidity goes down.

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