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Warm fronts

  • rodcarey
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rodcarey created the topic: Warm fronts

Hi All,

Could you please clarify within the CPL Meteorology page 117 q 29
Which of the following weather situations would be most likely after the passage of a warm front in the southern hemisphere
A Nil
B Heavy Rains
C Thunderstorms
D Isolated showers

On page 78 fig 5.7, i see Nimbostratus, Altocumulus and Altostratus, all associated with some weather type. If i were to pick the answer, it would be B ie Heavy rains associated with Nimbostratus, but the answer is stated as A. Is the devil in the detail of the question ie "after the passage" Could you please clarify? Thanks Rod

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bobtait replied the topic: Warm fronts

You've answered your own question. "after the passage" not "during the passage". Fig 5.7 shows that. In fact, warm fronts are almost never seen over Australia. They form to the south of the continent and move south. I have never seen one on a weather map in my long life.

Because the cold air is retreating and the warm air is flowing in behind it at a higher speed, the warm air overtakes the retreating cold air and, since it is less dense, it runs up over the sloping surface of the cold air (see attached figure). Once that happens, if the warm air is moist, extensive cloud forms ahead of the surface position of the warm front. Until it encounters the cold air mass, the warm air would be passing over the cold ground that was recently occupied by the cold air. That would create a very stable situation with very little or no convection occurring. Since there is no other mechanism to lift the warm air before it reaches the front, there would be a rapid clearing of the weather.

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