When did the sleet cool down for the first time after Beijing stopped heating?

On March 24th, 20 17, a light rain moistened the capital, and Beijing ushered in the first sleet cooling after stopping heating up. Yesterday, it rained lightly in the whole city, and snowflakes floated on the top of Buddha in Yanqing and in Xiaohaituo. The highest temperature is only 8℃. Today, the highest temperature continues to drop, and it is expected to be only 6℃. Everyone should pay attention to adding clothes.

This light rain "sneaked into the night with the wind". The air in Beijing was wet and cold yesterday, which made people feel that it was winter again. Without sunshine and rain, the highest temperature yesterday only climbed to 8℃, 6℃ lower than the previous day.

According to the meteorological department, due to the influence of cold air, there was light rain in the city from the night before yesterday, among which it snowed at Foyeding and Xiaohaituo in Yanqing. Rainfall first appeared in the south of Beijing, then developed from south to north, and spread all over the city around 2 am yesterday.

According to statistics, as of yesterday 14, the city's average precipitation was 4.4 mm, urban area was 4.7 mm, southwest area was 6.4 mm, southeast area was 4.8 mm, northwest area was 3.8 mm, and northeast area was 1.8 mm; The heaviest rain falls in Changyang, Fangshan, with a total precipitation of 12.8 mm.

Huang, a senior engineer of the Municipal Professional Meteorological Observatory, analyzed that by noon today, there was still light rain in most parts of Beijing, with an average precipitation of 4-6 mm, and the largest in Changping and Yanqing was 8-20 mm. As the cold air gradually moves southward, the temperature continues to drop. At about 5 o'clock this morning, the precipitation will turn from rain to sleet or snow, especially in the western and northern regions. It is expected that there will be small to medium snow in Changping and Yanqing, and heavy snow and sleet in Fengtai, Haidian, Shijingshan and Mentougou.

Meteorologists say it is normal to snow in March. From March 65 to March 20, 2065438, there was an obvious snowfall in Beijing, and the snowfall reached the magnitude of heavy snow. The usual year-end snow day in Beijing is 17 in March, and the western and northern mountainous areas are in early April. The latest final snow appeared in mid-May, and the date of final snow was delayed with the elevation. From this point of view, the last snow in the plain this year came a little late, but it was within the normal range.

This wave of cooling and rain and snow will prevent Beijing from entering spring. The reporter learned that the average daily temperature in Beijing last week was 10℃, and the flowers were ready to move. However, just as Beijing was looking forward to spring, a precipitation hit the capital hard. It is predicted that the average temperature will drop to 8. 1℃ this Sunday, so it seems that we have to wait for spring.

Last week, Beijing was as warm as spring, but after the vernal equinox, it was always rainy and foggy. Why is the contrast so big?

Zhang Mingying, a senior engineer of the Municipal Meteorological Observatory, told reporters that the recent rainy weather in Beijing is related to stratocumulus clouds.

Clouds are a sign of the weather and also indicate the future changes of the weather. Zhang Mingying explained that the appearance of stratocumulus is likely to cause stable and continuous light rain, generally not heavy rain. It has been raining since the "Spring Equinox" solar term (March 20th) until yesterday, which just fulfilled the weather proverb "Spring Equinox Rain to Sunny", which means that it rains on the day of the spring equinox solar term, and there will be more rain in Tomb-Sweeping Day.

What are the clouds when smog appears? Zhang Mingying said that the clouds that often appear with smog weather are called stratus clouds, which are gray foggy clouds, like a veil and lifeless. I believe there is no need to describe it. Everyone is already familiar with this kind of cloud.

How to "know the weather from the clouds"

Yesterday was the annual World Meteorological Day, and this year's theme is "Seeing the clouds and knowing the sky". So what kind of clouds represent what kind of weather?

Zhang Mingying, a senior engineer of the Municipal Meteorological Observatory, introduced that clouds are divided into three families 10 genera and 29 categories internationally. Generally speaking, low clouds are common, just like cotton, white clouds in the blue sky are also our favorite clouds. But sometimes low clouds have a great influence on the weather, such as cumulonimbus clouds and nimbostratus. Cumulonimbus clouds can cause bad weather. The characteristic of this cloud is that the convection inside the cloud is particularly strong and the air flows up and down very fast. Thunderstorms, strong winds, thunder and lightning, hail and other weather phenomena can often be seen, and the harm of such clouds is also relative.

Bigger. There will also be long-term and large-scale heavy precipitation in nimbostratus, but compared with cumulonimbus clouds, the rainfall is relatively stable.

There is also a cirrus cloud, which belongs to the high clouds. The shape of the cloud is silky and very white. The appearance of cirrus clouds is often a precursor to the coming weather system and will not have an immediate impact on the weather. If there are cirrus clouds such as hooked cirrus clouds and cirrostratus in the sky, they may become cumulus clouds, high-level clouds and finally nimbostratus with the increase of cloud volume and the thickening of clouds.

In fact, clouds are very complicated. There are many folk weather proverbs about clouds, such as "fish scales in the sky, no need to turn over grain in the sun", "cloud hooks are hanging in the sky, and rain is dripping on the ground", "the sky in the east is cloudy, and the clouds in the west wear hemp fiber", "Don't go out in the morning, travel thousands of miles at night", "It rains at night, and the moon is windy at noon" and so on. These are all based on the shape of the cloud. However, the weather forecast is only based on clouds and needs to be calculated by integrating other meteorological factors, such as temperature, humidity and other data changes. The ancients did not have the current observation instruments and methods, and they could only judge the weather by looking at the clouds. Weather proverbs are a summary of ancient people's experience, which has certain regularity, but they are one-sided, regional and not universal enough, so it is necessary to synthesize other materials.