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Name: Amer
Status: other
Grade: other
Location: CT
Country: N/A
Date: 8/17/2005


Question:
What is a weak cold front? How can one determine the trength of a cold front?


Replies:
"Weak" and "strong" fronts (sometimes warm, sometimes cold) is determined by the difference in atmospheric pressure across the direction of motion of the atmosphere. "Weak" fronts refer to smaller pressure differences in pressure. "Strong" fronts refer to larger differences in pressure. Associated with such fronts is also the temperature difference. "Cold" fronts refer to higher temperature in the direction of movement of the front. "Warm" fronts refer to lower temperature in the direction of the movement of the front. Large pressure/temperature differences also affect the speed at which the pressure gradient moves with respect to the ground. Large pressure/temperature differences usually result in faster moving fronts. This is an oversimplification, however, because the "strength" of a front is affected by moisture content as well as the vertical profile of the air pressure and temperature. A front can have a larger or smaller pressure difference depending upon the altitude. All of these atmospheric mechanics are "feedback" mechanisms, that is, it is usually not possible to separate the differences out -- one factor influences the affect of the other factors -- and vice versa.

Vince Calder


Amer,

This is a great question! A weak cold front could be defined in two ways (one or both conditions may occur):

1) When the difference in temperature in front of and behind the front is only a few degrees.

2) When the movement of the front is very slow.

David R. Cook
Atmospheric Physics and Chemistry Section
Environmental Assessment Division
Argonne National Laboratory


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