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Hello ultraviolet light is a kind of light that is shorter than the wavelength of visible light, and it can be divided into three types according to the wavelength: A light: The short-term effect will cause redness, tanning, and photosensitive reactions, and in the long term, it will produce wrinkles, dark spots, and aging.
B light: The short-term effect is redness, tanning, and sunburn, and the long-term effect will cause wrinkles, dark spots, and cancer. C Light:
Because the ozone layer cannot reach the surface, it cannot be seen in the short term, but it will produce ** cancer in the long term. We can clearly understand that it is b-rays that are easy to cause sunburn; In other words, when you happily go to the beach and get red and sore, and you shed a layer of skin, it is the short-term effect of ultraviolet B light. The "indoor ultraviolet tanning method" is to use the principle of "seeking good fortune and avoiding evil", avoiding ultraviolet B light and only using ultraviolet A light, so that the tanning effect can be achieved in the short term, but there is no concern about sunburn.
That is, in a machine equipped with many ultraviolet A tubes, the exposure time is gradually increased to achieve the purpose of gradual darkening. Of course, whether "black" and "beauty" can be equated is a matter of opinion. Health education often says that you need to spend more time in the sun to be healthy, saying that in this way you will have sufficient vitamin D; This is only half true.
According to research, except for infants and young children, we only need a little sun exposure every day to meet our body's needs for vitamin D. Unless you're like the little dragon girl who hides in the tomb all year round, it's not easy to be deficient in vitamin D. Ultraviolet rays for our human body, except for such a little benefit, are almost all disadvantages.
For example, wrinkles, dark spots, aging and cancer are the long-term effects of ultraviolet rays on us, and these long-term effects will not appear for a while, but accumulate over time, causing "irreversible" damage to our **. The whiter our skin tone, the less melanin, the weaker our resistance to ultraviolet rays, and the faster the "irreversible" damage accumulates. Therefore, the West has long vigorously promoted the concept of "more sun exposure is unhealthy", and the Food and Drug Administration of the United States is actively trying to stipulate that the "indoor ultraviolet radiation method" can only be applied to certain diseases.
Of course, we Orientals have a darker complexion and a slower accumulation of "irreversible" damage, so we don't care, but when wrinkles, dark spots, and aging have appeared, it's too late! Therefore, I would like to remind all of you who want to become a "black beauty" to be careful of the long-term cumulative effect of ultraviolet rays. If you must catch the "Kuroshio", please don't forget to do sunscreen according to the ultraviolet index forecast of the Daily Meteorological Bureau on weekdays, otherwise it will be difficult to solve wrinkles, dark spots, and **aging in the future.
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Good and bad are relative, for the coastal level rises, the coast is flooded, and tropical storms increase, which is bad from this point of view, but for the North and South Poles, it is not so cold there, and people can enter life.
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1.The Sun is a very massive celestial body, and with the Sun, the rotation and revolution of the celestial bodies of the solar system can be maintained according to gravity.
2.The sun can shine and heat, the sun's light allows us to see things, the ultraviolet rays in the sun can kill germs, the infrared rays in the sun are also useful, and the sunlight also allows plants to photosynthesize.
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Plants release oxygen through solar photosynthesis, grow, and bear fruit, so that humans can have food and survive.
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You can't survive without the Sunman.
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There are too many of them, which can generate electricity, promote photosynthesis, and basking in the sun in winter is very beneficial to **......
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Without the sun, the earth will not be able to rotate, maybe it will change to a straight line, and maybe one day the earth will hit Mars. Landlord, you are too imaginative to ask such a question.
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All plants need photosynthesis and you say what's good.
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The landlord should think the other way around, if there is no sun, what are the disadvantages, and you can't say this because you are afraid of being tanned.
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Radius: 695500 km.
432,200 miles.
109 Earth.
Volume: 1,300,000 Earth.
Volkswagen: 332900 Earth.
Density: grams cubic centimeters.
of the Earth's surface area is 1990 times.
Gravity: Twenty-eight times the gravity of the Earth's surface.
Length: Day of Earth Day.
Surface temperature: 500-5
V-type spectrum of G2 phase.
Luminosity: Ergo seconds.
Age: 4.6 billion years.
Hydrogen composition. Helium pro, hand-beaten, very tired, begging to adopt.
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The mass is almost hundreds of thousands of times that of the Earth.
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