Super Typhoon "Capricorn"
It has landed in Wenchang, Hainan and Zhanjiang, Guangdong
Causing serious disasters
Quite a few places
The photos of sealing doors and windows are out of the circle
But
Some netizens pointed out
It's better to have tape than not to tape
Why is Typhoon Capricorn so strong?
Is it useful to put "rice" shaped tape on the window?
Popular science is coming!
Why is this autumn typhoon so strong?
Schematic diagram of the typhoon generation process.
In meteorology, typhoons are clearly divided into summer typhoons (formed between June and August) and autumn typhoons (formed between September and November) according to the month in which they are formed.
Typhoon "Capricorn" formed at 2 p.m. on September 1 and officially became a member of this year's autumn typhoon. It is not only the strongest autumn typhoon to make landfall on the mainland in history, but also the strongest typhoon to make landfall on the mainland after Typhoon No. 9 "Rammasun" in 2014.
The main reason why autumn typhoons are so powerful is because of the higher sea temperatures in autumn. After the summer solstice, the direct point of the sun recedes from the Tropic of Cancer to the south, and the subtropical ocean surface is heated for the second time, and the sea surface temperature reaches the highest of the year. With the abundant nutrients provided by the warm ocean, the typhoons generated at this time generally grow strong and strong, and their huge size is particularly striking on satellite cloud images.
The direct sunlight point moves southward, and the surface temperature of the sea is warmer.
This time, Typhoon Capricorn was born from a tropical disturbance off the coast east of the Philippines and eventually developed into the strongest typhoon of the year (so far) under the right conditions.
Does tape work?
Many people have given different answers to this question.
Li Yongle, a physics teacher at the High School Affiliated to the Beijing National People's Congress, once said on social media: "Judging from the results of several experiments in mainland Taiwan and United States, tape is actually useless for typhoon prevention." The United States Bureau of Atmospheric and Oceanic Affairs even warns that taping can cause large pieces of broken glass, which is more likely to injure people. ”
He said that changing the glass to tempered glass is a better way to prevent typhoons. Tempered glass with steel frame can withstand most typhoons.
Friends who are interested in related views can find the original video to understand.
If you want to know the answer, let's do an experiment first.
When the fixed weight weights were dropped vertically at 10 cm and 20 cm heights, the glass was not broken. But when the height rises to 30 cm, the vertically falling weights directly smash the glass to pieces.
After taping the glass, the weight also falls vertically from 30 cm. This time, the glass is intact.
When the weight rises to a height of 40 cm, after falling vertically, a crack appears in the glass, but it does not shatter.
Through the test, it is not difficult to find that after the tape is applied, the glass can indeed resist the impact of heavy objects to a certain extent, reducing the possibility of glass breakage.
Lo Jueqiang, a former engineer of the Department of Mechanical Engineering of the Hong Kong Polytechnic University, said that when a storm occurs in a foreign country, windscreens are generally added, so there is no additional effect on the windows, but the situation in Hong Kong is different, and windshields are generally not added.
What is the most effective way to apply adhesive tape?
The purpose of sticking tape is to play a protective role, so how to apply the tape to maximize the effect?
When Typhoon "Mangkhut" passed through, some netizens posted pictures of tape.
Lu Jueqiang explained that there are three main reasons for glass bursting when the wind blows, including debris being blown up by the wind and breaking the glass; The wind speed is large, so that the glass oscillates to produce an oscillation frequency, which produces a resonance effect and shatters the glass; Glass is bent and deformed by strong winds, resulting in breakage.
According to research, the most vulnerable position of the glass on the window is the center, so it is reasonable to increase the bearing capacity of the glass when the tape is applied to the center position. However, in Lu Jueqiang's view, the most recommended way to paste the "rice" shape.
The "m" shape sticking method can not only change the natural frequency of the interference glass, reduce the probability of resonance effect, and make the glass not easy to break. At the same time, even if the glass is broken, the fall range can be better controlled. In addition, this can not only save the amount of tape, but also ensure indoor lighting, which is more suitable for general household use.
Liu Shujiang, an associate professor at the School of Materials Science and Engineering at Qilu University of Technology, also pointed out that it is best to use a diagonal cross or "m" shaped pasting method to paste the tape, and it is best to paste it outside the window frame, so that the center of the glass has a better support point.
In addition, the protective effect of the "rice" shaped tape is related to its thickness. Tapes with a certain thickness and elasticity should be selected, so the yellow sealing tape has a better effect.
How do I clean up tape marks?
If you don't want to painstakingly clean the tape marks on the glass, the best way is to remove the tape in time after a typhoon. Because the adhesive on the tape will gradually dissolve over time, the more time passes, the more difficult it is to clean.
Stubborn adhesive tape traces can be wiped with a small amount of alcohol, wind oil essence or white oil, etc., and they can be removed.
Negative pressure phenomenon under super typhoon and countermeasures
When a typhoon comes, strong winds create fast-moving air currents around buildings. When the wind blows from one side of the building at high speed, it will reduce the air pressure on this side, while the other side of the building, if it is relatively closed, will form a pressure difference with the wind side, resulting in negative pressure.
Du Fu Shiyun: "The high wind roared angrily in August and autumn, rolling up the triple thatch on my house. "It's because of the difference in air velocity between the inside and outside of the house, the pressure difference caused by it topples the roof.
On the morning of September 7, many trees on both sides of the road in Leizhou urban area had been uprooted and fell on the road. Some of the storefront's billboards have also been blown open or blown away. Photo by Southern + reporter Zhong Zhihui, Wu Ming, Wu Dongjun
Negative pressure mainly has these hazards:
- Cracked windows: If the pressure difference between the inside and outside of a building is too large, windows may crack because they can't withstand the pressure. This is especially likely to happen in some old buildings or in poorly installed windows.
- Difficult to open: Negative pressure may make the door sucked in tightly, making it difficult to open. This may hinder the evacuation of people in an emergency.
- Roof damage: For some light roof structures, negative pressure can cause the roof to be lifted or damaged.
Safety measures to deal with negative pressure during typhoons:
- Check windows and doors: Before a typhoon, check the tightness of windows and doors to make sure they are closed securely. If there is a gap in the window, it can be sealed with sealing strip or tape to reduce the effect of negative pressure. Before a super typhoon, seal or seal doors and windows decisively.
- Reinforcement of the roof: For light roof structures, reinforcement measures can be taken, such as installing wind clips, adding heavy objects, etc., to prevent damage to the roof caused by negative pressure.
Forward to remind family and friends
Source: Nanfang Daily
Editor/Producer: Tang Yuandong
Reviewer: Li Man
Review: Liu Chunxiang