Extreme cold weather in North America

(1) high or low? Increase and strengthen (4 points)

(2) North America's topography is columnar in north and south, and the middle is flat and open, wh

(1) high or low? Increase and strengthen (4 points)

(2) North America's topography is columnar in north and south, and the middle is flat and open, which is conducive to the long-term southward drive of polar cold space (3 points)

Test analysis: The higher the temperature, the higher the air near the ground expands when heated, which leads to the decrease of air density and air pressure. On the contrary, the air pressure rises. The problem 1 refers to the frequent occurrence of extremely cold weather in Europe and Asia, and the Eurasian region where extremely cold weather broke out is mainly located in the high latitudes of the northern hemisphere, so the temperature and pressure in this region are higher than normal. It can be seen from the "balance" that the air pressure in the mid-latitude area is lower than normal. The pressure difference between middle and high latitudes increases, so the horizontal pressure gradient increases. Under the strong horizontal pressure gradient, the cold air flow from high latitudes increases. The topography of North America is clearly divided into three north-south longitudinal zones, namely, the western part is a tall mountain system, the central part is a vast plain, and the eastern part is a low highland. Central North America is a plain, which is not blocked by tall mountains. A cold current from the Arctic Ocean can reach the Gulf of Mexico.

Comments: The key to solve this problem is to read the question, fully understand the meaning of the question, find the key word "extremely cold", understand the meaning of "one is changing and the other is growing", and find out the relationship between the four spaces in the first question. The second problem is to master the topographical features of North America and its influence on the climate, which is something to remember.