Why did the snowstorm hit Texas? What are the relevant climate knowledge points?

In the past week, a snowstorm hit Texas in the United States, causing more than 4 million households to lose power and more than 14.9 million people to have no access to water, attracting global attention.

At the same time, many places in southern Europe and Greece were hit by rare heavy snowfalls, with water and electricity cut off and schools closed.

Why did the snowstorm suddenly hit the southern United States and Greece, which is famous for its desert and scorching sun?

In fact, there are many reasons for blizzards. There are three main factors for this year's blizzards in the southern United States

Where is the cold air?

We often hear about the cold air in Siberia. In fact, Siberia is not the origin of cold air, but a source station of cold air crossing the Antarctic.

The earth receives different solar radiation at different latitudes and the polar regions receive less heat, while the equator receives the most heat. This leads to low temperatures on the earth's surface, high pressure, increased atmospheric temperatures in the equatorial regions, and The surface pressure drops, and the stratosphere shows lower pressure than the upper atmosphere in the Arctic, so the formation of the polar vortex is called a polar vortex.

Every winter, under normal conditions, the polar vortex in the stratosphere will be strongly surrounded by westerly winds. The cold air at this time is very cold. China's natural climate has relatively small temperature fluctuations.

However, under abnormal conditions, the polar vortex in the stratosphere can be affected by disturbances, deformations, or collapses.

Who broke the curse of the cold air?

As we all know, factors that affect weather occur in the lower stratosphere, causing atmospheric changes, so civilian aircraft cannot fly, and sometimes interact with the troposphere, which affects our weather.

The changes in the stratosphere over the Arctic from 2020 to the early end of 2021 are typical.

The sudden increase in stratospheric temperature is due to the propagation of low-level atmospheric waves into the stratosphere.

The above picture shows the temperature changes in the middle stratosphere from about 30km to 10hPa. We can see that the temperature in the Arctic region rose rapidly within a month. In the first year of 2021, it suddenly rose to only five days, in Temperatures in the polar stratosphere.

Polar stratospheric thermal anomalies associated with weak or clockwise rotation.

It usually takes about two weeks for the temperature in the stratosphere to rise from convection to explosion to affect the troposphere. Strong warming of the stratosphere does not occur every year, nor does it affect the weather and climate in the same area every year. It will inevitably affect Europe and the United States.

Why are snowstorms hitting Texas and Athens?

First of all, the cold wave pushed the Arctic vortex to the south, so in the past ten days, Europe and North America have become more and more obvious in the northern hemisphere.

Secondly, affected by terrain factors, if the earth is relatively flat, the natural speed will be low and the consumption will be low. Otherwise, the speed will be slow and the consumption will be large. Therefore, there will be less obstruction by the cold air from the oceans and plains.

There are many mountains in the western United States, the Central Plains and the eastern flats. This time, the cold air from the Central Plains to the east of the Rocky Mountains, when the cold, warm air and moist Gulf of Mexico cold wave dominates the warm air The coordination with moisture resulted in large-scale snowfall.

With the intensification of global warming, extreme weather and extreme climate in February are abnormally warm. In North America, northern China and Europe, the climate in Huanghuai and other places is very cold and may break the record in the future. Temperatures, we may experience summer warming, more severe convection.