Were hot, humid summers the key to life's origins?

Uncovering how the first biological molecules (like proteins and DNA) arose is a major goal for researchers attempting to solve the origin of life. Today, chemists at Saint Louis University, in collaboration with scientists ...

Product authentication at your fingertips

Imagine if water vapor in your breath or surrounding your fingertips revealed invisible patterns on commercial products—smartphones, laptops, expensive liquor—that verified the products' authenticity and aided anticounterfeiting ...

Heat, humidity keeps hold on Eastern US as weekend slogs on

A heat wave will continue to keep much of the Eastern United States in its grip Sunday, while a cold front that could lower temperatures in the middle of the country may be accompanied by thunderstorms that threaten flash ...

From rain to flood

Extreme weather events such as thunderstorms, heavy rainfall and resulting floods, influence Earth and environmental systems in the long term. To study the impacts of hydrological extremes holistically—from precipitation ...

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Humidity

Humidity is a term for the amount of water vapor in the air, and can refer to any one of several measurements of humidity. Formally, humid air is not "moist air" but a mixture of water vapor and other constituents of air, and humidity is defined in terms of the water content of this mixture, called the Absolute humidity. In everyday usage, it commonly refers to relative humidity, expressed as a percent in weather forecasts and on household humidistats; it is so called because it measures the current absolute humidity relative to the maximum. Specific humidity is a ratio of the water vapor content of the mixture to the total air content (on a mass basis). The water vapor content of the mixture can be measured either as mass per volume or as a partial pressure, depending on the usage.

In meteorology, humidity indicates the likelihood of precipitation, dew, or fog. High relative humidity reduces the effectiveness of sweating in cooling the body by reducing the rate of evaporation of moisture from the skin. This effect is calculated in a heat index table, used during summer weather.

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