Xiao Bian has always thought that wearing white in the summer is the best ~ black heat absorption ~ wear heat for a while will feel ~ What is the most sunscreen color in summer? Let's take a look with Xiaobian~ Experimental equipment: black, white, red T-shirts each, 3 thermometers; long exposure, red clothes, sunscreen best, white worst Experiment I: Short-term exposure for 5 minutes, white is the coolest 3-color (red, black, white) cotton T-shirt of the same specification. At about 12 o'clock noon, the sun was slamming and three clothes were placed on the cement floor near the roof of the building. At the same time, a thermometer was placed on each garment. As the ground temperature was too high for 5 minutes, the thermometer on the red T-shirt and black T-shirt showed more than 40°C, while the thermometer on the white T-shirt showed 38.7°C. Experiment 2: After 20 minutes of drying, the red is the coolest The same device was moved to a straw mat and a new experiment was conducted on a terrace where it could be sun-dried. The temperature at the outside of the room was about 32°C. Tested on mats, this time the thermometer did not burst the watch, the time of the sun was extended to 20 minutes, the test results have changed, the thermometer on the red T-shirt shows the lowest number, 36.5 °C, white and black T-shirt The thermometers showed numbers of 37.1°C and 36.9°C and the situation was "inverted." According to the experimental results, it was found that the short-term exposure of the white T-shirt was cool, and the long exposure to the red T-shirt was cool. Within 5 minutes of exposure, the temperature of the white T-shirt is obviously lower than that of the black T-shirt and red T-shirt; after 20 minutes of drying, the red T-shirt is lower in temperature than the white T-shirt and black T-shirt, and the white sunscreen The worst effect. expert's point: The red light has a longer wavelength and can absorb a large amount of ultraviolet light in sunlight, and the sunscreen has the best effect. According to the results of the experiment, the physics teacher explained that dark clothes absorb heat quickly, and white clothes absorb less heat and can reflect ultraviolet rays. Therefore, in a short time, it is relatively cool. Although light-colored clothing reflects some ultraviolet rays, it is not able to absorb ultraviolet rays. Because the red light has a longer wavelength, it can absorb a large amount of ultraviolet rays in sunlight, and the sunscreen has the best effect. Therefore, if you are in the sun for a long time, wear red clothes more coolly. It is understood that Harvard University has done an experimental study, the results show that wearing dark clothing in summer is cooler than wearing white clothing. Experts point out that the heat in the human body can be emitted by radiation, conduction, convection and evaporation. It is true that black clothes absorb more heat than white clothes, but the absorbed heat can become a convection force in the clothes (as in the summer afternoon, the ground is heated to form local convective weather, such as thunderstorms, which cools the weather. ), the air convection inside the clothes, you can take away the sweat and some of the heat on the skin surface, the body will naturally feel cool. Of course, black clothes should be made loose so that "convection" can be strengthened and the coolness of clothes can be increased. In addition, wearing black clothes indoors or on cloudy days will give it a fast heat dissipation function, which will quickly drain away the heat from the skin surface, leaving you feeling cool. The teacher pointed out that it is cool to wear black clothes when there is no sunlight. It can be worn indoors or on a cloudy day. Since there is less sunshine during this time, black will not exhibit the nature of absorbing heat quickly. Instead, it will only exert its ability to dissipate heat quickly, so that the heat on the surface of the skin can be rapidly drained. Naturally, It feels cooler than other colors of clothes. The UV protection ability of clothes depends not only on the color but also on the material. The SPF value (sun protection value) of cotton clothes is 15~40; the SPF value of light colored polyester clothes is 7~10; the SPF value of light colored knitted clothes is 4~9; the bare arm skin is best to use yarn Shawl and sleeve protection. So, if you want to prevent UV rays, it is best to wear dark cotton clothes. The less summer you wear, the less you can wear it. For the experiment, some citizens were asked. Many people think that in order to be cool, they can wear clothes that are as small as possible without sleeves. However, such a cool dress is really good? "In fact, the summer is not necessarily the less you can wear more heatstroke." Dr. Chen of the First Affiliated Hospital of Hangzhou told reporters that if the temperature exceeds 35 °C, the skin is not only not cool Instead, it will absorb heat and cause heat stroke. It is understood that in the temperature of 18 °C to 28 °C, 70% of human body temperature by the skin radiation, convection and conduction heat, the temperature reached 35 °C, mainly by the skin evaporation heat. When the temperature continues to rise, the skin not only cannot dissipate heat through radiation, but also absorbs heat from the external environment. Not only does it not feel cool, but the increase in body surface temperature makes people feel hotter, and it is exposed to high temperatures for a long time. It is easy to cause heat stroke. In the summer, many men like to play shirtless and feel cool. However, this is a misunderstanding. When the temperature approaches or exceeds the human body temperature (about 36.8°C), not only is it not cool, but it is even hotter. "Because the shirtless skin can increase the radiation of the skin and conduct heat dissipation only when the skin temperature is higher than the ambient temperature." Faster clothes get hotter In the summer, many people like to wear clothes that have a quick-drying function. However, as a result of the experiment, clothes that have a quick-drying function may cross the heat. The reason is that although the clothes are quick-drying, they are poor in hygroscopicity. The inspector first compared the water absorbency between the quick-drying clothes and the pure cotton clothes, and found that the cotton fabrics outperformed the quick-drying fabrics. Afterwards, the inspector placed the two samples in a constant temperature laboratory for experimentation. The laboratory temperature is constant at 22°C and the relative humidity is maintained at 68%. Twenty-four hours later, the inspectors took 100 grams of each sample and removed it from the laboratory. The experimental results show that 100 grams of pure cotton fabric can absorb 8 grams of water while 100 grams of quick-drying fabric can only absorb 0.4 grams of moisture. Experts say that fast-drying fabrics are mainly chemical fiber polyester fabrics. Although the fabrics are light and thin, they have poor water absorption and air permeability. Relatively speaking, pure cotton has good air permeability and water absorption. "Natural fibers such as silk, cotton and hemp are all good summer clothes." You know you should wear it in the summer. 230T Twill,Twill Lining Fabric,Polyester Twill Lining,100%Polyester Twill Lining WUJIANG ZHONGTIAN JETWEAVING CO.,LTD , https://www.zhongtianfabric.com
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