Causes of extreme weather in North America

North America, especially the United States, has the most changeable extreme weather in the world: there are so many extreme weather hurricanes, tornadoes, droughts, floods, mountain fires, blizzards, heat waves and cold currents anywhere on earth. Why is the weather in North America so extreme? The following is a study. Bian Xiao carefully sorted out the causes of extreme weather in North America. Let's see. The indirect cause of extreme weather events in North America is the background of global warming, and the direct cause is the persistence of atmospheric circulation anomalies and its response to sea surface temperature changes. (1) Global warming has regional characteristics. One of them is that the heating rate in high latitudes in the northern hemisphere is different from that in middle and low latitudes, which leads to the decrease of meridional pressure gradient force in middle and high latitudes. Once the westerly basic airflow weakens, the trough bed and ridge movement in the middle and high latitudes will weaken and continue to control some areas, leading to extreme weather and climate events. (2) The sea surface temperature anomaly and its distribution pattern in the North Atlantic Ocean and the relatively low sea surface temperature in the Indian Ocean have caused great differences in the thermal power between land and sea in the Indian monsoon region, providing conditions for the continuous anomaly of atmospheric circulation. On the one hand, Britain, Germany and Russia in Europe are affected by cyclone circulation (low pressure system), and extreme weather and climate such as storms appear; On the other hand, the North American continent maintains a deep high-pressure system at latitude 30 north and south of Beijing, resulting in extremely hot weather. In the Indian region of Asia, due to the great difference between land and sea, the Indian summer monsoon is strong, which leads to frequent extreme precipitation in the Indian mainland. Extreme weather may be more and more. According to the monitoring results released by the World Meteorological Organization, the trend of global warming has not changed. In the past 15 and 16 years, most of them were among the best in the list of the hottest years since meteorological records were recorded in the world. Global warming is a fact. Under the background of climate warming, extreme high temperature, extreme low temperature, blizzard, drought and heavy precipitation will also appear. Zhou Botao pointed out that, for example, from the end of 2012,65438+year 10 to the middle of February, the worst high temperature drought occurred in Eurasia in the past half century, the worst high temperature drought occurred in the United States in summer, and severe droughts occurred in Yunnan and southwest Sichuan in winter and spring. With global warming, the original climate law has been broken, and the climate has become more abnormal, farther and farther from the average, and the vibration is getting bigger and bigger, leading to more and more extreme weather. The climate is not just a small-scale anomaly as before, but runs around the average. Many strange weather, either drought or heavy rain. For example, the rainstorm in Beijing. Zhou Botao said. How to deal with the changing climate? Zhou Botao stressed that it is necessary to raise awareness of low-carbon environmental protection, and start with small things such as driving as little as possible to protect the climate. At the same time, extreme weather events will occur frequently in the context of global warming.