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 ...

Beewolves use a gas to preserve food

Scientists from the Universities of Regensburg and Mainz and the Max Planck Institute for Chemical Ecology discovered that the eggs of the European beewolf produce nitric oxide. The gas prevents the larvae's food from getting ...

A polar-bear-inspired material for heat insulation

For polar bears, the insulation provided by their fat, skin, and fur is a matter of survival in the frigid Arctic. For engineers, polar bear hair is a dream template for synthetic materials that might lock in heat just as ...

Extreme heat to hit one third of the African urban population

Climate change, population growth and urbanization are instrumental in increasing exposure to extreme temperatures. Researchers at the University of Geneva (UNIGE), Switzerland, – in collaboration with the University of ...

Neotropical cloud forests to lose what most defines them: clouds

In as few as 25 years, climate change could shrink and dry 60-80% of Western Hemisphere cloud forests, finds a study published today. If greenhouse gas emissions continue increasing as they have been, 90% of Western Hemisphere ...

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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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