Energy & Green Tech

New insights lead to better next-gen solar cells

For Michael Saliba and Mahdi Malekshahi, it was one of those moments in science when good experimental results raised more questions. The University of Stuttgart researchers recently developed a new process to make solar ...

Energy & Green Tech

Engineers use moisture to pull carbon dioxide out of the air

In a corner of Kelsey Hatzell's lab sits a small jar filled with a material that has an ability far beyond what its nondescript appearance would suggest: a way to capture and release carbon dioxide from the atmosphere by ...


Video: A picking robot for the greenhouse

Working in a greenhouse is both strenuous and time-consuming. The picking robot from ETH spin-off Floating Robotics takes on particularly repetitive tasks, thereby alleviating the strain on human pickers. It is currently ...


New research may point the way towards frost-free heat pumps

A chilly winter morning, the car windshield shrouded in a thick layer of frost. Who has not experienced the frustration of scraping ice or waiting for the defroster to work? It is a daily winter struggle, but what if this ...

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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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