The weather on February 2 nd.

(1) northerly wind or northwest wind (1)? 2 1 day wind is greater than 20 days. ( 1)

The reason for the judgment is that Ganzhou is in a cold front transit on 2 1 day, and the isobar is denser than on the 20th. (2 points)

(2) Change: On the 20th, the air pressure was low (or1006-1008), the temperature was high and the weather was fine. (2 points)

2 1 day air pressure rises (or 1008— 10 10), the temperature drops, and rainy weather occurs. (2 points)

Reason: Ganzhou was controlled by the heating group before the cold front crossed the border on the 20th. 2 1, Ganzhou is experiencing (or being affected by) a cold front. (2 points)

(3) Typhoon (or strong tropical cyclone) will bring heavy precipitation and raise the river level; (1) In mountainous and hilly areas of Fujian Province, landslides and mudslides caused by heavy rains are easy to block rivers; (1) Storm surges in coastal areas will also raise the river level. ( 1)

(1) This topic investigates the formation of wind. The horizontal movement of the atmosphere is called wind, and the direct cause of wind is the horizontal pressure gradient force, which is perpendicular to the isobar and points to the low pressure. At high altitude, the wind direction is only affected by the horizontal pressure gradient force and geostrophic deflection force, and the wind direction is finally parallel to the isobar; Near the ground, the wind direction is also affected by friction, and the wind direction finally intersects the isobar. On September 2 1 day, the wind in Ganzhou is northerly. Within two days, the isobars became dense and the wind speed increased.

(2) Before the cold front crossed the border on the 20th, Ganzhou was controlled by a warm air mass. On the 20th, the air pressure was low, the temperature was high and the weather was fine. 2 1 day, Ganzhou is passing through a cold front, the air pressure increases, the temperature drops, and rainy weather appears.

(3) Figure L 1 shows a tropical depression. The intense development of tropical depression can form a typhoon, bring heavy precipitation and raise the river level. In mountainous and hilly areas of Fujian province, landslides and mudslides caused by heavy rains are easy to block rivers; Storm surges in coastal areas will also raise the water level of rivers.