In the spring of Hangzhou, you have to wear a mask

Yesterday, it was expected that the temperature of 28°C did not appear. It was a hazy day. The Hangzhou practitioners who had exercised in the morning started to open the window yesterday and found that the air was bad. Today, the Hangzhou Environmental Protection Bureau predicts that the air quality is still moderately polluted, so go out and do some protective work.

In terms of weather, Hangzhou is cloudy and cloudy during the day. During the night, showers start to turn cloudy; tomorrow, there are showers or thunderstorms, and the rainfall is moderate.

Convective clouds block the sunlight

North Zhejiang temperature is blocked

Yesterday morning, I went out of my shoes and I remember wearing a very cool little watch because the weather station forecast had a maximum of 28°C. Unexpectedly, at 9:00 in the morning, the sky was suddenly clouded, the breeze wafted, and a heavy rain was about to come. Poor I was wearing my sleeve and my arms were cold and goose bumps.

They quickly asked the provincial meteorological station. They said that there was a convective cloud group moving eastward. The previous day did not expect its impact to be so great. Affected by the eastward movement of convective cloud clusters, the dark clouds in northern Zhejiang are still covered with rain. Although the rain did not form a scale, it was only a light rain, but the clouds filtered out the sunlight.

Without the help of the sun, only the warm and moist air is fighting alone, and the temperature certainly cannot rise so high. Yesterday, the highest temperature in Hangzhou was 25.9°C. While in the south of Zhejiang Province where there was no convective cloud cluster, the temperature easily climbed 30°C. Wenzhou Wencheng, the highest in the province, was 33.9°C. Lishui Yunhe and Qingtian followed, reaching 33.2°C.

During the daytime, most of the province is cloudy to cloudy. However, from the evening onwards, the rains have hit again and some parts of our province will have moderate to heavy rain.

Tomorrow is the weekend and the weather is not very good this weekend. Hangzhou Meteorological Observatory said that due to the influence of cold air, there will be showers or thunderstorms tomorrow, and the rainfall will be moderate; the rain will stop on Sunday and Hangzhou will be cloudy.

This is mainly due to the recent warm and humid air flow. The weak cold air can be used to squeeze out rain. This pattern will continue until the 22nd. Prior to this, showers were frequent visitors. After the 22nd, we may be able to invite a few days of good weather, I suggest that we always pay attention to the newspaper's WeChat public number, "God knows."

After the rain, strong temperature inversion and steady weather conditions

Easy to form high humidity haze days

In people's minds, rain can wash away the pollutants in the air. Yesterday, it rained in Hangzhou. It is reasonable to say that the air should be fresh. However, yesterday's sky was overcast in Hangzhou, and a long time no longer appeared.

Starting early in the early hours of the morning, Hangzhou's air quality index AQI has been hovering around 150. Starting at 7 am, AQI gradually began to climb. From 10 am to 1 pm, it walked near 200 points, and then the peak turned back and left. At 6 o'clock in the afternoon, the Hangzhou AQI index dropped to 142 and was lightly polluted. However, individual points, such as Hexun Elementary School, with an index of 224, are heavily polluted; the Zhaohui District of the urban area is moderately polluted with an index of 160.

The environmental protection department said that the primary pollutant in the air is PM2.5, prompting residents to wear masks, pay attention to protection, and close doors and windows.

Why is it raining and the air quality is still so bad? "After rain, it is likely to form a high-moisture haze weather under strong weather conditions," said Peng Yingdeng, a researcher at the National Urban Environmental Pollution Control Technology Research Center. Heavy rain does wash away pollutants from the air, and the air is fresh after the rain. However, if there are static weather conditions that are not conducive to the diffusion of pollutants immediately after the rain, the high humidity will intensify the formation and accumulation of secondary particles, resulting in an increase in the concentration of PM2.5, which will result in heavy haze.

In contrast, yesterday, Hangzhou began to rain, but the rain is not large, the air humidity is basically between 70% to 85%, and there is still a little inversion at around 8:00 am; the wind is not large, only 9 o'clock in the morning and more convective clouds There was a gust of wind when the group arrived, and the wind in Hangzhou was very weak. Both wind speed and wind power are small, which is not conducive to the dilution and diffusion of pollutants. The moist air also “puts on” a layer of “water coats” for suspended pollutants, which is more likely to cause the accumulation of pollutants and increase the concentration of smog.

Today's air quality or moderate pollution

Temporary heavy pollution emergency plans will not be activated for the time being

Many citizens are concerned that the sky in Hangzhou these days is gray, and the air quality index APP on mobile phones also shows that some monitoring points are heavily polluted for quite a few hours. So, will Hangzhou launch an atmospheric heavy pollution emergency plan?

According to the “Hangzhou Atmospheric and Heavy Pollution Emergency Preparedness Plan (Trial)”, the early warning level of atmospheric heavy pollution is divided into Level I, Level II, and Level III, respectively marked with red, orange, and yellow.

The standard for starting Class III early warning (yellow warning) is monitoring and forecasting that the city’s air quality in the next 2 days is heavily polluted, ie, the air quality index (AQI) is between 201~300; Class II early warning (orange warning) It is monitored and predicted that the urban air quality in the next 2 days in Hangzhou is seriously polluted, that is, the air quality index (AQI) is between 301 and 450; the Class I early warning (red warning) is monitored and forecasted, and the air quality in Hangzhou city will be 1 day The quality is extremely heavy, ie, the Air Quality Index (AQI) is above 451.

In other words, if yesterday's Hangzhou is heavily polluted and today is forecasting heavy pollution, it will start a Class III warning. However, according to the joint forecast of the Hangzhou Meteorological Observatory and the Hangzhou Environmental Protection Monitoring Department, the air quality forecast for Hangzhou today is 180~200, which is moderate pollution, so the emergency plan is not started for the time being.

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