Because of the sinking motion of the cold air behind the front and the resultant adiabatic warm-ing, the temperature change across the front is often destroyed or may even be reversed. A sound-ing taken in the cold air immediately behind the surface front indicates only one inversion and an increase in moisture through the inversion. Farther back of the front, a double inversion structure is evident. The lower inversion is caused by the subsidence effects in the cold air. This is sometimes confusing to the analyst because the subsidence inversion is usually more marked than the frontal inversion and may be mistaken for the frontal inversion.

In contrast to the slow-moving cold front, the wind above the fast-moving cold front exhibits only a slight backing with height of about 20 degrees between 950 and 400 mb; the wind direc-tion is inclined toward the front at an average angle of about 45 degrees. The wind components normal and parallel to the front increase with height; the wind component normal to the front exceeds the mean speed of the front at all levels above the lowest layers.

On upper air charts, the isotherms are NOT parallel to the front. Instead they are at an angle of about 30 degrees to the front, usually crossing the cold front near its junction with the associated warm front.

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