介绍： 版权归原作所有，仅供此学习，若有侵权请告知删除。
[12:10.26]The last reading.
[12:13.48]Front
[12:15.21]A front is a weather system that is the boundary separating two different types of air.
[12:21.65]One type of air is usually denser than the other,
[12:26.04]with different temperatures and different levels ...

介绍： 版权归原作所有，仅供此学习，若有侵权请告知删除。
[12:10.26]The last reading.
[12:13.48]Front
[12:15.21]A front is a weather system that is the boundary separating two different types of air.
[12:21.65]One type of air is usually denser than the other,
[12:26.04]with different temperatures and different levels of humidity.
[12:30.20]This clashing of air types causes weather: rain, snow, cold days, hot days, and windy days.
[12:38.99]Two major types of fronts are cold fronts and warm fronts.
[12:43.92]Normally cold fronts come with thunderstorms or other types of extreme weather.
[12:49.91]They usually move from west to east.
[12:53.10]Strong, powerful cold fronts often take over warm air
[12:57.06]that might be nearly motionless in the atmosphere.
[13:00.62]This movement is called a low-pressure system,
[13:04.64]which often causes severe rainfall or thunderstorms.
[13:08.81]Warm fronts usually show up on the tail end of rain, snow, hail and fog.
[13:15.81]As they overtake cold air masses,
[13:18.81]warm fronts move slowly, usually from north to south.
[13:23.89]Warm fronts are often associated with high-pressure systems,
[13:28.43]which usually indicate calm, clear weather.