High school geographic weather system

The warm front is the initiative of the warm air mass and the cold front is the initiative of the cold air mass.

Air pressure flows from high pressure to low pressure. It should be noted that if you want to judge the direction of air flow, you can only compare the air pressure on the same horizontal plane. At the same level, the air pressure is high in cold places.

I don't know if this knowledge point is unclear:

1 2

3 4 Like 1234, if the elevations of 1 and 2 are the same, the elevations of 3 and 4 are the same, and the elevations of 1 and 2 are higher than 3 and 4.

If 1234 forms a circulation, if 3 and 2 are relatively high (2 1 cold, 3/4 cold), then the wind direction changes from 3->; 4，4->2，2-> 1， 1->； This forms a cycle. It is impossible for 3 to be high pressure 1 or low pressure, so 3 flows to 1 and the air pressure needs to be compared on the same horizontal plane.

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Manual only. .