蘇明坤

Humidity refers to the amount of water contained in the air. As the air's temperature changes， so does theamount of water the air can hold.

濕度指的是空氣中所含的水分。隨著氣溫變化，空氣中的水分含量也會(huì)變化。

One of the ways your body cools itself is by sweating. The sweat then evaporates from your skin， and it carriesheat away from the body as it leaves.

身體自我冷卻的方式之一就是出汗。汗水從你的皮膚表面蒸發(fā)時(shí)，會(huì)帶走身體的熱量。

However， humidity throws a wrench in that system of evaporative cooling. As relative humidity increases， theevaporation of sweat from your skin slows down. Instead， the sweat just drips， which leaves you with a damp T-shirtand none of the cooling effect. When the humidity spikes， we effectively lose a key tool that would normally cool usdown.

然而，濕度卻會(huì)讓蒸發(fā)冷卻機(jī)制失靈。隨著空氣中的相對(duì)濕度增大，汗水從皮膚表面蒸發(fā)的速度則會(huì)減慢。停留在皮膚表面的汗水會(huì)把你的T恤浸濕，而且一點(diǎn)也不會(huì)讓你感到?jīng)隹臁．?dāng)濕度很高時(shí)，我們實(shí)際上失去了一個(gè)自我降溫的法寶。

When we think of wind on a hot day， we think ofa nice， cooling breeze. That's the normal state of affairs， butwhen the weather is really， really hot-think high-90s hot-a dry wind actually heats us up. When it's that hot out，wind actually draws sweat away from our bodies before it can evaporate to help cool us down. Thanks to this effect，what might have been a cool breeze acts more like a convection oven.

當(dāng)我們想到熱天里的風(fēng)，我們想到的是清涼宜人的微風(fēng)。正常情況下是如此的，但是當(dāng)天氣非常非常熱的時(shí)候（比如高于32攝氏度時(shí)），干燥的風(fēng)其實(shí)會(huì)讓我們更熱。在天氣很熱時(shí)，風(fēng)會(huì)在汗水尚未蒸發(fā)時(shí)就將其吹干，從而讓我們無(wú)法借助汗水蒸發(fā)來(lái)降溫。也正因如此，大熱天里的風(fēng)不僅不能帶來(lái)涼意，反而更像是烤箱的對(duì)流加熱。

However， being in the shade can make quite a big difference. Direct sunlight can add up t0 15 degrees to the cal-culated heat index.

不過(guò)，在陰涼處則會(huì)有很大不同，因?yàn)殛?yáng)光直射會(huì)讓炎熱指數(shù)上升15度之多。