When winter comes every year, many friends both like and fear it. What they like is that winter is the only time of the year that is so white. Although the time is short, it leaves us with a different scenery. What I’m afraid of is that the temperature is so low in winter that many of our friends can’t stand the cold.
corresponds to winter. For summer, although the weather is also hot, the range of activities that people can do has expanded a lot. Especially in modern times, we can even simulate winter scenes in summer, which is another scene.
When it comes to winter, each of us thinks of snow, while in summer it is high temperatures. In fact, in summer, "cold phenomena" will also occur. The more common one is hail. This is a phenomenon that involves natural disasters, especially many of our friends in rural areas do not like it very much.
When it comes to hail and snowflakes, from the perspective of climatology , these two phenomena are actually caused by water vapor encountering cold air in the air. This is an introduction that many of our friends are very familiar with, but when it comes to the reasons for the formation of this phenomenon, if we think carefully, we will still find something "wrong".
For example, the formation of snowflakes and hail is caused by water vapor being cooled in the air, and to form hail, the temperature required is lower. But when we return to the climate conditions, we will find that the temperature is lower in winter. It stands to reason that it is easier to form hail in winter.
The fact is just the opposite. In real life, we will find that it almost always snows in winter, but it does not snow in summer and is more likely to hail. What is going on? Let's take a look at this issue today.
The formation process of snowflakes and hail
First, let's take a look at how snowflakes and hail are formed. In fact, the formation processes of snowflakes and hail are relatively similar, both related to water vapor.
Before mentioning hail and snowflakes, we have to understand another thing, that is clouds, which we can often see in the sky. Some friends say clouds are water droplets, while others say clouds are water vapor.
In fact, clouds are composed of small water droplets or ice crystals, or both. They are small water droplets formed by precooling and liquefying water vapor in the atmosphere, small ice crystals formed by condensation, or a polymer formed by a mixture of the two.
The formation of snowflakes is related to small ice crystals. The flower-like snowflakes we see are also because snowflakes are formed by the condensation of small ice crystals. When the ice in the clouds When crystals and water droplets continuously collide and evaporate, water vapor is formed, and the volume of water vapor gradually increases during the condensation process. In addition, the structure of ice crystals is hexagonal, so after the ice crystals increase, they become "flower" shaped. This is the process of snowflake formation.
Hail tends to emphasize a sharp drop in temperature. Similar to the formation process of snowflakes, when clouds encounter low temperatures, the liquefied clouds will use dust in the air as crystal nuclei and turn into water droplets or ice crystals. When exposed to low temperatures, they turn into larger water droplets and fall to the ground. This is our common rainfall.
There is another situation here, that is, the cold air encountered does not have enough time for the clouds to form crystal nuclei. At this time, the clouds will condense into ice or snowflakes, and ice or snow will appear. If the temperature drops very quickly, the clouds will form relatively large ice masses, which will become the hail we see when they fall to the ground.
Conditions for the formation of hail
Friends who have seen hail falling can find that when hail begins to fall, the weather changes are very obvious and relatively common. The most common thing is that the sky suddenly gets dark, and black clouds appear in the sky. The black clouds we see are what we often call hail clouds . Many experienced old people know that hail is coming when they see the clouds. Indeed, hail is formed in hail clouds, and it is generally related to the following factors.
① There are sufficient unstable clouds in the atmosphere: hail itself comes from clouds. If you want to form a larger ice mass, you must have sufficient ice crystals and small water droplets. In meteorology it is generally required that the moisture content of cumulonimbus reaches 3 to 8 grams per cubic meter.
② There are sufficiently thick and huge clouds: The so-called thick and huge clouds are what we often call cumulonimbus. Such clouds can cause larger water droplets to condense into ice. According to meteorology, its temperature can reach -16 to -12 degrees Celsius.
③ Strong wind shear occurs: What is strong wind shear? In fact, this phenomenon is related to a word we mentioned above, that is cumulonimbus. Wind shear refers to the changes in wind speed and direction in the horizontal and vertical distances in the air. When cumulonimbus clouds or thunderstorms weather appear in the sky, strong convective weather can easily form and strong wind shear can occur.
In summary, it is not difficult to find that although the temperature is not low in summer, the exposure to the sun causes water vapor to evaporate and condense quickly, which meets the requirements for rapid hail formation. Although the temperature is lower in winter, the overall temperature changes are relatively balanced, making it difficult to meet the conditions for hail formation. #headline creation challenge#
