Emergency geographical problems: geographical natural disasters: cold wave, summer drought, plum rain?

Cold wave: a large-scale cooling phenomenon in late winter, early spring, late autumn and early winter, accompanied by strong winds, rain and snow, is called cold wave, which is caused by the rapid southward invasion of cold air carried by Mongolian Siberian high pressure. 2. Summer drought: it is the drought along the Yangtze River in dog days. The Yangtze River area in dog days is controlled by the subtropical high belt. 3. Meiyu: In early summer, there are often long rainy days in the Jianghuai Basin. At this time, the utensils are easily moldy, so it is called "mildew rain", and when the plums in the south of the Yangtze River are yellow, it is also called "plum rain" or "Huang Meiyu". It is caused by the long-term stagnation of cold and warm air. What I want to mention here is how rainfall is formed. When it rains, it is formed because cold and warm air masses meet. When one side is dominant, the rainfall will pass, and when both sides stay in a certain area, this area will form continuous rainfall. A typhoon is a tropical cyclone, and the air pressure in the center of the typhoon is extremely low, which will suck the nearby air into the center. 6. Storm surge: Abnormal fluctuation of seawater makes the tide level in the affected sea area greatly exceed the normal tide level, usually caused by strong wind or typhoon. 7. Tidal flat: it is the general name of beach, river beach and lake beach. At present, beaches generally refer to coastal beaches. 8. Wind current: Definition: The prevailing wind blows the sea surface and pushes the sea water to drift with the wind, so that the upper seawater drives the lower seawater to flow and form a large-scale ocean current, which is called wind current. (Cause: The wind direction in trade winds, westerly winds and polar easterly winds is relatively constant. In the ocean, there will be friction between these directional winds and the surface water. Through friction, wind can transfer some energy to surface water, which not only forms waves, but also causes surface water to move, thus forming airflow. )