Warm, Cold, and Dry Conveyor Belts

Warm conveyor belt -

• Originates at low levels in the warm sector

Dry conveyor Belt -

• Originates at upper levels and descends to the surface
• Often produces a region of clearing skies behind the cold front.
• Here is an example of the clearing produced by the cold, dry air descending to the surface

Cold Conveyor Belt -

• originates NE of low, swirls into the low at then ascends to upper levels

QUESTIONS FOR THOUGHT:

1. Explain why at 500 mb, when cold-air advection is occurring, the air temperature does not drop as fast as it should.

2. Over the earth as a whole, would you expect the atmosphere to be mainly barotropic or baroclinic?  Explain.

3. Baroclinic waves seldom form in the tropics.  Why?

4. If you only had isotherms on an upper-level chart, how would a cut-off low appear?

5. Identify regions of cold-air advection and warm-air advection today over the U.S. and Canada.  By looking at representative soundings, how do the winds at low levels change direction with height in the region of cold-air advection and warm-air advection? 

6. Assume that the lapse rate is 6.5 degrees Celsius per kilometer here at LSC.  If cold-air advection is occurring aloft such that at 500 mb (6 km AGL) the rate of cooling is 0.2 degrees Celsius per hour, what will be the resultant lapse rate 6 hours later?  Has the atmosphere stabilized or destabilized?