Key for Homework 6

 

  1. How are cold fronts different from stationary fronts? How are cold fronts different from drylines? How are cold fronts and drylines alike?

    Cold front and stationary fronts are very similar, except that on a cold front the cold air mass is pushing the warm air mass out of its way, whereas on a stationary front neither the warm air mass nor the cold air mass is successfully pushing the other air mass out of the way. Cold fronts and drylines differ in that the density differences across a cold front are caused by temperature differences, whereas the density differences across a dryline are caused by moisture differences. Cold fronts and drylines are alike in that they both slope back over the more dense air mass with respect to height.

     

  2. Name three types of fronts that are examples of the "polar front". Why are the other two types of fronts NOT examples of the "polar front"?

    Cold fronts, warm fronts, and stationary fronts are all examples of the polar front. Drylines and occluded fronts are not examples of the polar front because they don't represent regions where cold air from the north is encountering warm air from the south.

     

  3. Where would you look for rain associated with a warm front--north of the front or south of the front? Why?

    Rain would be found NORTH of the warm front. This is where the overrunning is occurring.

     

  4. Which kind of front is more steeply sloped--cold front or warm front? Which kind of front moves more quickly--cold front or warm front? Which kind of front is associated with stratus clouds--cold front or warm front?

    Cold fronts are more steeply sloped. Cold fronts move more quickly. Warm fronts are associated with stratus clouds.

     

  5. Consider the following meteogram, which is from St. Louis during a recent 24 hour period:

     
    • At what time did a front pass through St. Louis?

      About 5Z

    • What kind of front do you think it is? What factors lead you to this conclusion?

      It was a cold front, due to the wind shift, temperature change, and dewpoint change.

    • Describe how the weather changed as this front passed through. Be sure to mention changes in temperature, winds, dewpoint and pressure.

      As the cold front passed, winds shifted out of the north, temperatures fell, and the dewpoint fell. Pressure fell until the front passed, then pressures rose.

     

  6. Consider the following meteogram, which is from Charleston, South Carolina during a recent 24 hour period. (The temperature, dewpoint and pressure curves are in the same place as they were on the previous diagram--I just didn't take the time to label everything again by hand. Use the diagram from St. Louis to remind yourself about which curve is which.)

     
    • At what time did a front pass through Charleston?

      About 8Z

    • What kind of front do you think it is? What factors lead you to this conclusion?

      It was a warm front, due to the temperature changes and wind shift.

    • Describe how the weather changed as this front passed through. Be sure to mention changes in temperature, winds, dewpoint and pressure.

      Winds shifted out of the southwest, temperatures rose, and the dewpoint rose. Frontal passage was marked by a minimum in the pressure.

     

  7. Answer the following questions about drylines:
    • In what part of the country do you typically find drylines?

      Texas, Oklahoma, Kansas, etc.

    • What two types of air masses are typically separated by drylines?

      cT and mT

    • Which of the two air masses listed in the previous question is MORE DENSE?

      cT

     

  8. True or false: A stationary front is depicted on weather maps by alternating triangles and half circles on opposite sides.

    True.

     

  9. True or false: An air mass source region is an area of significant weather including strong winds.

    False.

     

  10. What is overrunning? What kinds of clouds are the result of overrunning?

    Overrunning is the situation in which a warm air mass primarily slides over the top of a cold air mass, rather than dislodging it from its location. You expect stratus clouds in such a region, particular nimbostratus, altostratus, and cirrostratus.