Warm and/or moist waiting encroaching top top a fixed of cooler or drier air results in a heat front. Warm and also moist waiting is normally less thick than cold and also dry air and also will conveniently "ride" over the optimal of cool air. Accordingly, a warmth front does not represent an abrupt or sudden contrast, as does a cold front (Figure 9.29).




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Fig. 9.29 warmth moist air conveniently rides over chillier air once impinging ~ above it.

Warm fronts are stood for on weather maps together a red line with "half suns" ~ above the leading edge (Figure 9.30).


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Fig. 9.30 explicate of warmth front in a mid-latitude cyclone.

The leading edge of a heat front may have a 30,000 foot or greater altitude and also be thousands of miles in advance of the line at floor level separating warm and cold. As the heat air lifts over the cool air, it too cools and also at some level condensation begins. The first indication of one approaching heat front might be cirrus clouds (or persistent contrails) adhered to in time by altostratus and also then stratus clouds (Figure 9.31), and also possibly widespread and general rain (or snow). Return not thought about as violent together weather events linked with a cold front, warmth fronts room usually the reason of glaze or freezing rain that can cripple activity of traffic and break trees and power lines. Also, heavy basic rains the can happen may an outcome in widespread flooding, together opposed to intense flash flooding often caused by a thunderstorm.


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The wind readjust around a heat front goes native easterly or southeasterly ahead of the front come southerly of southwesterly behind it. Unequal the cold front, advance notice of a warmth front is an extremely apparent. Cirrus clouds portend the advance of a warmth from 24-36 hrs ahead. These clouds are produced by the heat air gift lifted to really high levels in the atmosphere. Behind the warm front the dew point and temperature boost as the air mass changes from a cP wait mass come a mT waiting mass. Precipitation can occur, however is much more showery kind as opposed to the thunderstorm kind of the cold front. The comprehensive cloudiness front of the warmth front quickly gives way to clean skies. The elevator disappears ~ the prior passes. Pressure is normally falling till the former passes, then it may rise slightly as the heat sector the the cyclone overcome over.




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Fig. 9.32 A warmth front is illustrated from southerly Canada across the Dakotas. Click image to enlarge.


Usually, the contrast across the heat front is no as to mark as throughout a cold front. However changes can be seen. Ahead of this heat front there is some cloudiness, yet not as extensive as typically occurs. This is probably because the air right here is very dry after coming off the mountains. The fronts top top this map are attracted from 2 hours prior to these observations. Therefore, locations of the eastern Dakotas are more than likely behind the warmth front.