Beware¹ of Wind Chill²

人们都知道，在温度相同的情况下，有风的冷天会比无风的天气感到寒冷。那是因为人体产生的热量会温暖体外薄薄的一层空气，对我们的体温有保护作用。而有风的天气这层暖空气会被吹散，加速体温的流失。在加拿大，每年都有近80人因寒冷而死。

Anyone who's been outside on a windy, winter day knows it's a lot more difficult to stay warm than on a calm day with the same temperature.

On a calm winter day, our bodies warm up a thin layer of air close to our skin -- called the boundary layer -- and that helps to insulate³ us from the cold air. However, when the wind starts to blow, it strips away this boundary layer and our skin is more exposed to the cold air.

Because wind chill speeds up the rate at which your body loses heat, it can be dangerous. Each year in Canada, more than 80 people die from overexposure to the cold.