T： Too much outdoor lighting is a problem in many cities nowadays.
What are the causes and negative impacts of light pollution in cities？
In many areas, the use of lighting outside leads to a phenomenon known as light pollution. The following essay focuses on the factors behind this problem and describes some of the ways scientists, animals and members of the public can be negatively affected by excessive amounts of lighting.
Among the different types of pollution affecting our planet today, light pollution is unique in that it is solely caused by human activity and technology in urban areas.[1] When large structures, such as stadia, train stations and department stores are illuminated, the light is emitted directly into the sky. [2]Another major cause is advertising which is commonplace in cities. [3]Large hoardings, for instance, are often lit with spotlights which point upwards and a significant amount of light is reflected up into the night sky. [4]Finally, many companies and members of the public use electric lights/glaring lamps for decorative purposes. [5]This is most obvious during big festivals such as Christmas when shops and houses use fairy lights to make their premises more attractive.[6]
Light pollution has a variety of unfortunate consequences affecting diverse groups. [1]Scientists studying the night sky, by way of example, are unable to make observations near cities and are forced to relocate to remote areas. [2]As a result, observatories are usually constructed on the peaks of mountains or on isolated islands, which increases the expense involved. [3]In addition, [nocturnal] animals may be attracted to the light emitted from cities and this can interfere with their migration routes and breeding patterns. [4]For example, my city is full of white birds called egrets which never seem to sleep as a result of the light pollution in the area.[5] Finally, urban residents rarely have an opportunity to appreciate the stars and the planets since only the brightest celestial objects are visible.[6]
In summary, light pollution has a variety of causes, but they all stem from the human desire to create artificial light/brightness. However, light pollution can have severe consequences for both humans and animals, so we should take steps to reduce it if possible.
整个人口生活在极端程度的人为夜晚时间的明亮当中。
人工亮光更加严重
耀眼的灯
在城市的各个广场上，霓虹灯交替闪烁
霓虹灯；霓虹灯广告
In the city squares the neon lights flashed in turn. [making the nights never get dark ]
在城市的各个广场上，霓虹灯交替闪烁。
neon lights/signs 霓虹灯；霓虹灯广告
the entire population lives under this extreme level of artificial night-time brightness
the artificial glow was even greater
glaring lamps
点亮的广告牌，
体育场 PL
天文台
广告牌x3 大幅广告牌
白鹭
天体
耀眼的灯泡
夜行动物，夜里迁移的鸟类
人工灯光，人工点亮的户外地区
对农作物授粉是一个威胁---减少夜行昆虫的授粉行为
减少光污染的同时节省能源
光污染正在阻碍天文学：世界上三分之一[的地区]看不到银河系。
stadium C stadia OR stadiums
observatory [C.]
hoarding n. /ˈhɔːdɪŋ/
1.( BrE ) [C] ( NAmE BrE also bill·board ) a large board on the outside of a building or at the side of the road, used for putting advertisements on 大幅广告牌
2.[ C ] ( BrE ) a temporary fence made of boards that is placed around an area of land until a building has been built （建筑工地用木板搭起的）临时围栏
3.[ U ] the act of hoarding things 贮存；聚藏；（尤指）秘藏
advertising hoardings 大幅的广告牌
A billboard is a very large board on which posters are displayed
egret [c] 白鹭
celestial bodies (=the sun, moon, stars etc)天体
premises n. /ˈpremɪsɪz/ [PL]
business/commercial/industrial premises 事务所；商业╱工业用房屋场地
• No alcohol may be consumed on the premises . 场区内禁止饮酒。
Schools may earn extra money by renting out their premises. 学校通过出租房屋场地可以获取额外收入。
business premises 企业经营场所
[C.] a statement or idea that you accept as true and use as a base for developing other ideas (also 又作premiss)
The idea that there is life on other planets is the central premise of the novel. 其他星球存在生命这一观点是这部小说的核心前提。
The premise is that schools will work harder to improve if they must compete.
前提是各学校如必须竞争就会更加努力改进。
.an illuminated sign.
...一个灯光闪烁的招牌
a beautiful starry night 繁星满天的美丽夜晚
lights that are shielded, or can dim or turn off while not being used, could help to reduce light pollution as well as save energy.
light pollution is hindering astronomy: a third of the world now cannot see the Milky Way.
More than 80% of the world's population lives under light-polluted skies, a study suggests.
Scientists explain in Science Advances how ground measurements and satellite data were used to create an atlas of a world brightened by artificial lights.
It reveals that the population of Singapore, Kuwait and Qatar experience the brightest night skies.
Conversely, people living in Chad, Central African Republic and Madagascar are least affected by light pollution.
Dr Christopher Kyba, from the German Research Centre for Geosciences in Potsdam, said: "The artificial light in our environment is coming from a lot of different things.
"Street lights are a really important component, but we also have lights from our windows in our homes and businesses, from the headlights of our cars and illuminated billboards."
The brightness map reveals that 83% of the world's population, and 99% of Europeans and people in the US, live under skies nearly 10% brighter than their natural starry state.
For some though the artificial glow was even greater, said Dr Kyba.
"About 14% of the world's population don't even use their night-time vision," he explained.
"The night is so bright that they use their colour daytime vision to look up at the sky."
In Singapore, the entire population lives under this extreme level of artificial night-time brightness, and it is a problem affecting many other parts of the world.
"Twenty percent of the people in Europe and 37% of the people in the US don't use their night vision," said Dr Kyba. "It's really an enormous number."
Many people do not have to use their black-and-white night vision to look up at the sky
He added: "In the UK, 26% of people are using colour vision and not night vision."
The researchers warn that nights that never get darker than twilight are affecting nocturnal animals, while in humans, the trend has been linked to sleep disorders and disease.
Dr Kyba said that while lighting was important for development and safety, technology needed to improve.
"There are a lot of street lights that are not particularly well designed," he explained.
"They shine light into areas that are not useful - so up into the sky, for example, isn't really useful for anybody.
"There's a big difference between having a well-lit street, which means everybody can get around really easily and safely, and a brightly lit street, which could mean there's too much light and it's not helping anyone."
The researchers say better designed street lighting could help to cut light pollution
The paper suggests that lights that are shielded, or can dim or turn off while not being used, could help to reduce light pollution as well as save energy.
The researchers add that light pollution is hindering astronomy: a third of the world now cannot see the Milky Way.
A study of pictures of Earth by night has revealed that artificial light is growing brighter and more extensive every year.
Between 2012 and 2016, the planet's artificially lit outdoor area grew by more than 2% per year.
Scientists say a "loss of night" in many countries is having negative consequences for "flora, fauna, and human well-being".
A team published the findings in the journal Science Advances.
Their study used data from a Nasa satellite radiometer - a device designed specifically to measure the brightness of night-time light.
It showed that changes in brightness over time varied greatly by country. Some of the world's "brightest nations", such as the US and Spain, remained the same. Most nations in South America, Africa and Asia grew brighter.
Only a few countries showed a decrease in brightness, such as Yemen and Syria - both experiencing warfare.
The nocturnal satellite images - of glowing coastlines and spider-like city networks - look quite beautiful but artificial lighting has unintended consequences for human health and the environment.
Let the Sun go down
In 2016, the American Medical Association officially recognised the "detrimental effects of poorly designed, high-intensity LED lighting", saying it encouraged communities to "minimise and control blue-rich environmental lighting by using the lowest emission of blue light possible to reduce glare. The sleep-inducing hormone melatonin is particularly sensitive to blue light.
A recent study published in the journal Nature revealed that artificial light was a threat to crop pollination - reducing the pollinating activity of nocturnal insects.
Research in the UK revealed that trees in more brightly lit areas burst their buds up to a week earlier than those in areas without artificial lighting.
A study published earlier this year found that urban light installations "dramatically altered" the behaviour of nocturnally migrating birds.
Lead researcher Christopher Kyba from the German Research Centre for Geoscience in Potsdam said that the introduction of artificial light was "one of the most dramatic physical changes human beings have made to our environment".
The brightest parts of the UK are getting brighter
He and his colleagues had expected to see a decrease in brightness in wealthy cities and industrial areas as they switched from the orange glow of sodium lights to more energy-efficient LEDs; the light sensor on the satellite is not able to measure the bluer part of the spectrum of light that LEDs emit.
"I expected that in wealthy countries - like the US, UK, and Germany - we'd see overall decreases in light, especially in brightly lit areas," he told BBC News. "Instead we see countries like the US staying the same and the UK and Germany becoming increasingly bright."
Since the satellite sensor does not "see" the bluer light that humans can see, the increases in brightness that we experience will be even greater than what the researchers were able to measure.
Prof Kevin Gaston from the University of Exeter told BBC News that humans were "imposing abnormal light regimes on ourselves".
'Less light, better vision'
"You now struggle to find anywhere in Europe with a natural night sky - without that skyglow we're all familiar with."
Prof Gaston added that he found the continuing increase in light pollution curious. "Usually," he explained, "when we think of how humanity messes with environment, it's a costly thing to fix or reverse.
The Nile and surrounding region are outlined by light at night
"For light, it's just a case of directing it where we need it and not wasting it where we don't."
Dr Kyba said that we could make our urban areas much dimmer and not actually cause any problems for visibility.
"Human vision relies on contrast, not the amount of light," he explained.
"So by reducing contrast outdoors - avoiding glaring lamps - it is actually possible to have improved vision with less light.
"That could mean big energy savings - but our data show that on a national and global scale, this is not the direction we are heading."
