It is prevented by controlling the relative humidity of the circulating air and the temperature of the air.

控制循环空气的相对湿度和空气的温度可防止表面硬化的出现。

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The NWS Web site features a handy on-line calculator for determining the heat index based on a combination of either temperature and relative humidity or temperature and dew point.

国家气象局(NWS)网站公布了一个方便的在线计算器便于大家基于温度和相对湿度或温度和露点的结合来计算炎热指数。

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Relative humidity, a percentage, is the ratio between the water vapor present and the air's saturation point, a figure that changes with the temperature.

相对湿度，是空气中绝对湿度与饱和湿度的比值，它随着温度变化。

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Heat indices combine temperature and relative humidity to indicate how hot the body feels.

CNN: Heat wave sweeps across U.S. Northeast

The Met Office's "feels like temperature" takes into account expected air temperature, relative humidity and the strength of the wind at around 5 feet (1.5m) - the typical height of a person's face.

BBC: Who, What, Why: What is wind chill factor?

So depending on the relative humidity and temperature, 100 or more water molecules diffuse out of the leaf for every molecule of carbon dioxide that diffuses in.

WSJ: Harrison H. Schmitt and William Happer: In Defense of Carbon Dioxide