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同是10度天,为何秋天感觉比春天冷?

更新时间:2018-11-1 21:34:28 来源:纽约时报中文网 作者:佚名

Here’s Why a 50-Degree Day Feels Colder in Fall Than in Spring
同是10度天,为何秋天感觉比春天冷?

That first cold spell of the season always feels especially harsh.

这一季的第一次寒潮,总让人觉得分外的冷。

If you’ve ever wondered, from beneath several layers of clothing, whether you were overreacting to those frigid early fall days, take solace. It may not just be in your head: The human body takes time to acclimate to the cold.

如果你曾经想知道,穿着好几层衣服的你,是否对初秋的寒冷天气反应太过强烈,还是别想太多。可能不仅仅是你的大脑,你的身体也需要时间来适应寒冷。

“We kind of get a global response over time over the winter so that a 50-degree day in, say, February, feels glorious, whereas at this time of year it feels chilly,” said John Castellani, a physiologist who specializes in cold weather research at the United States Army Research Institute of Environmental Medicine in Massachusetts.

“随着时间的推移,我们对冬天产生了一种整体性的反应,所以,比如说二月里碰到一个10摄氏度的天气,我们会觉得很暖和,但如果每年的这个时候碰到,就会觉得好冷,”马萨诸塞州美国陆军环境医学研究所(the United States Army Research Institute of Environmental Medicine)研究寒冷天气的生理学家约翰·卡斯泰拉尼(John Castellani)说。

Some experts argue that the shift in perception is mostly psychological, but others, including Dr. Castellani, say there’s more to it: The evidence suggests that the body grows to tolerate the cold over time.

一些专家认为,这种感知上的转变主要是心理上的,但包括卡斯泰拉尼在内的另外一些人则认为,事情没有那么简单:有证据表明,随着时间的推移,身体对寒冷有一个逐渐适应的过程。

Here’s a brief look at what we do and don’t know about how the body responds to the cold in, say, autumn, compared to the spring.

下面简单介绍一下我们在秋天对寒冷的反应和春天有什么不同,其中哪些是我们已经知道的,又有哪些是我们还有待了解的。

We’re all snowflakes

我们都是娇气的雪花

As anyone who has fought over the thermostat knows, people experience temperature differently, sometimes dramatically so.

为了房间温度的高低设定而跟人发生争执的人都知道,人们对温度的感受是不同的,有时候差异非常剧烈。

A variety of factors explain why. Studies have found, for example, that larger people shed more body heat in the cold than smaller ones because they have a greater surface area over which to lose it. People with more fat beneath their skin lose less heat because it serves as insulation. And older people can have more difficulty with frigidity than the young.

个中原因不尽相同。比如,研究发现,因为体表面积更大的缘故,大块头比小身材会散失更多的身体热量。皮下脂肪厚的人身体保温效果更好。老人比年轻人更怕冷。

Psychology can play a substantial role, too. As can behavior: Humans excel at limiting their exposure to wintry conditions, which can dull the effects of the cold.

心理也是其中一个因素。还有行为也是如此:人类擅长避开寒冷的环境,这也会减弱寒冷的影响。

“There’s a classic saying that ‘man in the cold is not necessarily a cold man,’” said Mike Tipton, a professor of physiology at the University of Portsmouth in Britain who studies temperature regulation in the body. “We wrap up, we heat our houses, we wear clothes and we recreate our tropical origins next to the skin.”

“老话说‘身体是冷的,心是热的’,”英国朴茨茅斯大学(University of Portsmouth)研究人体温度调节的生理学教授迈克·蒂普顿(Mike Tipton)说,“我们把自己裹得严严实实,给房子供暖,穿上衣服,我们在周身重现了我们的热带起源。”

How the body responds

身体会做何反应

When the temperature drops, sensors in the skin known as thermoreceptors detect that change and send signals to the hypothalamus, a small, versatile region of the brain sometimes referred to as the body’s thermostat.

温度下降的时候,皮肤上的传感器,即所谓的温度感受器就会检测到这种变化,并向下丘脑发送信号。下丘脑是大脑中一个多用途的小区域,有时被称为人体的恒温器。

To maintain a safe core body temperature, the hypothalamus may then direct the body to do one of two things. The main response is a process known as vasoconstriction: the tightening of blood vessels on the body’s periphery to shunt warm blood away from the extremities and skin and back toward the core. The body may also shiver to generate heat.

为了保持安全的核心体温,下丘脑会引导身体做下面两件事中的一件。主要的反应是一个叫做血管收缩的过程:收缩体表血管,让温暖的血液从四肢和皮肤回到核心部位。身体还会通过发抖的方式产生热量。

“When the skin senses cold temperatures, its first response really is to protect the inside,” Dr. Castellani said.

“当皮肤感受到低温时,它的第一个反应就是保护体内,”卡斯泰拉尼说。

How the body adjusts

身体如何调适

Over time, though, those responses can change.

不过,随着时间的推移,这些反应可能会发生变化。

Studies of people throughout the world have found that those frequently exposed to the cold simply begin to tolerate it more by shivering or constricting blood vessels less.

对世界各地的人们进行的研究发现,那些经常暴露在寒冷环境中的人,仅仅是通过发抖或收缩血管就能变得更加耐寒。

Indigenous populations in the Australian and African deserts and the Arctic, for example, have been found to have a less pronounced response to the cold than those not subjected to the same frigid conditions. (Temperatures in the deserts often plummet at night.)

比如说,澳大利亚、非洲沙漠和北极地区的原住民,跟那些没有处在相同寒冷条件下的人相比,显著的身体反应要少(沙漠到了晚间往往气温骤降)。

The same has been found even among people subjected to the cold in more limited ways. For example, fishermen and fish filleters who work long hours with their hands in cold water have been found to have higher hand temperatures when their hands are placed in frigid water compared with control subjects. Similar effects have been found among slaughterhouse workers who routinely handle slabs of cold meat.

甚至在那些以特定方式暴露于寒冷中的人群身上,也发现了同样的情况。例如,渔民和处理鱼的工人需要把手长时间泡在冷水中,但研究发现,在冰冷的水中,他们的手温要高于对照组对象的手温。经常需要处理冻肉的屠宰场工人,也发现存在类似的情形。

That, Dr. Castellani said, explains how a person in a cool climate might adapt to winter over time.

卡斯泰拉尼说,这正好解释了一个在寒冷气候里的人是如何慢慢适应冬天的。

“We experience that cold air on our cheek all winter long, and basically that skin doesn’t constrict as much,” he said. “We’ve habituated in that area, and because the skin’s a little warmer that’s why it feels warmer. That’s why the cold October day feels much colder than that same day in February.”

“整个冬天我们都会感到寒气扑脸,但皮肤基本上不会有太大收缩,”他说。“我们的那个区域已经习惯了,由于皮肤温度更高,所以我们感觉也会更暖和。”这就是为什么人们对于同样的温度,出现在十月会比出现在二月让人觉得更冷。

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