大热天穿什么衣服最凉快？答案不是一件大白T那么简单。衣服的颜色、面料、松紧都会影响你的体感。

As the world continues to grapple with extreme heatwaves, which are becoming ever more regular thanks to climate change, the clothing we wear is a vital component in how we stay cool. Researchers have found that by wearing appropriate clothes, it is possible to turn the air-conditioning up by 2C (3.6F) – which over the long term would save considerable energy, both saving money and cutting greenhouse gas emissions.

全球还在继续与极端热浪作斗争，而且受气候变化影响这种极端天气越来越频繁，而我们所穿的衣服对于保持凉爽十分关键。研究人员发现，如果穿对衣服，空调可以调高2度，长期来看可以节省不少电，既能省钱，还能减少温室气体排放。

So what should you wear to stay cool?

那么穿什么衣服才会凉快呢？

Colour and design

颜色和设计

When it comes to colour, most people wear white in the summer – because white reflects the sun's rays, rather than absorbing the light like black does.

说到衣服颜色，大多数人在夏天穿白色衣服，因为白色能反射太阳光线，而不像黑色会吸收光线。

However, heat doesn't just come from the sun – it comes from our bodies too. When that heat from our bodies hits the white clothing, it is reflected back at us.

然而，不仅太阳会释放热量，我们的身体也会散发热量。来自身体的热量遇到白色衣服，就会反射回身体。

In 1980, a study of why Bedouins – an indigenous, semi-nomadic people who inhabit desert regions in the Arabian peninsula, Middle East and North Africa – wear black robes in the desert, found that heat exposure was the same whether tribal members wore black or white robes.

1980年，一项研究想知道在阿拉伯半岛、中东和北非的沙漠地区活动的半游牧原住民贝都因人为什么在沙漠中穿黑色长袍，结果发现，这些部落成员无论穿白色还是黑色长袍接触到的热量都一样多。

How is that possible?

这怎么可能呢？

Black coloured fabrics absorb heat emanating from the body – so this can also play a role in cooling your body down. The Bedouin's secret is wearing loose-fitting black clothing, especially if it's windy. The loose black clothes heat up the space between the fabric and the skin, promoting an upward air current – like a chimney – and providing cooling relief.

黑色面料吸收了身体散发的热量，因此黑色衣服有助于给身体降温。贝都因人的秘诀在于他们穿宽松的黑色衣服，尤其在有风的日子里。宽松的黑色衣服让面料和皮肤之间的空间升温，从而形成了向上的气流，就像烟囱一样，从而让身体凉爽下来。

So the fit of the clothing is actually more important than the colour. However, if you are going to be wearing tight-fitting clothing, then stick with white. Fabrics with texture – such as seersucker or pique, a fabric often used in sports polo shirts – also help to lift clothing off your skin.

所以衣服的松紧其实比颜色更重要。不过，如果你要穿紧身衣服，那就穿白色的。有纹理的面料，比如泡泡纱或翻领运动衫常用的珠地网眼面料，也有助于让衣服和皮肤不紧贴在一起。

Material matters

面料很重要

"In terms of clothes, it's better to have a material that allows water vapour to pass through so that it doesn't block the sweat evaporation." says Rhett Allain, associate professor of physics at Southeastern Louisiana University. "Some of the newer sports-based materials do this. Cotton does not do so great with this."

东南路易斯安那大学的物理学副教授瑞特·阿兰说：“衣服要凉快，最好是采用能让水蒸气通过的面料，这样才不会阻止汗液蒸发。有些新型运动面料能做到这点。棉布的透湿性则要差一些。”

Uncoated cotton, linen, nylon and polyester are all classed as breathable fabrics to some degree – meaning they allow sweat and heat to escape through the material.

没有涂层的棉布、亚麻、尼龙和涤纶都有一定的透气性，这意味着汗液和热气都能通过这些面料。

Cotton absorbs moisture but it doesn't dry quickly, so if you're sweating a lot your clothes will stay wet, making them less comfortable. Linen is widely worn as it has excellent breathability due to its large fibres, but like cotton it is slow to dry. Merino wool has been a popular choice for outdoor enthusiasts as it's breathable and wicks moisture without retaining odour.

棉布吸湿却不能速干，所以如果你流很多汗，衣服就会湿湿的不舒服。很多人爱穿亚麻衣服，因为亚麻的粗纤维赋予其极佳的透气性，但是和棉一样，亚麻干得慢。美利奴羊毛既透气又吸湿排汗而且不会留下汗臭味，因此受到户外运动爱好者的欢迎。

Nylon and polyester are used in most activewear as they wick moisture and dry quickly – but they retain odour. Research has also shown that nylon has a higher moisture absorption and better wicking capabilities than polyester, but is slower to dry. Synthetic fibres like nylon and polyester can feel uncomfortable when they get wet though, and one study suggested wearing clothing made of bamboo, which is a low conductor of heat, and doesn't compromise on comfort.

尼龙和涤纶吸湿排汗又速干，因此被应用在多数运动装中，但是这两种面料不防臭。研究表明，尼龙的吸湿排汗能力比涤纶更强，但是比涤纶干得慢。不过，尼龙和涤纶这样的化纤面料湿掉后会让穿着者感到不舒服。一项研究指出，穿竹子制成的衣服导热性低，而且舒适度高。

So it turns out that picking an outfit to stay cool is a little more complex than simply throwing on a white T-shirt. But the right fabric and appropriate fit when possible should help you keep your temperature down when the mercury heats up – and save on air-conditioning too.

可见，穿什么衣服才能凉快是个有点复杂的问题，不是一件大白T就能解决的。但是合适的面料和剪裁在大热天能帮你降温，也能节省空调电费。

英文来源：BBC

翻译&编辑：丹妮