Look at the figure "Schematic diagram of air pressure changes before and after the transit of different weather systems", in which the curves before and after the transit of typhoon and sandstorm are

Look at the figure "Schematic diagram of air pressure changes before and after the transit of different weather systems", in which the curves before and after the transit of typhoon and sandstorm are () a respectively. A

① When crossing the border, the central air pressure is low and it is a cyclone; ② When crossing the border, the central air pressure is high, which is an anticyclone; ③ After crossing the border, the air pressure rises, which is a cold front; ④ After crossing the border, the air pressure drops, which is a warm front. The weather systems corresponding to typhoons and sandstorms are cyclones and cold fronts, so the correct answer is A.