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Humidity is one of the fundamental abiotic factors that defines any habitat (the tundra, wetlands, and the desert are a few examples), and is a determinant of which animals and plants can thrive in a given environment. [28] The human body dissipates heat through perspiration and its evaporation.
When the two tendencies are in balance— and the air and food are stable—the air's relative humidity (expressed as a fraction instead of as a percentage) is taken to be the water activity, a w. Thus, water activity is the thermodynamic activity of water as solvent and the relative humidity of the surrounding air at equilibrium.
Plants absorb water from the soil, which then evaporates from their shoots and leaves; this process is known as transpiration.If placed in a dry environment, a typical mesophytic plant would evaporate water faster than the rate of water uptake from the soil, leading to wilting and even death.
T w = Natural wet-bulb temperature (combined with dry-bulb temperature indicates humidity) T g = Globe thermometer temperature (measured with a globe thermometer, also known as a black globe thermometer) T d = Dry-bulb temperature (actual air temperature) Temperatures may be in either Celsius or Fahrenheit; Indoors the following formula is used:
The Netherlands has around 4,000 greenhouse enterprises that operate over 9,000 hectares [57] of greenhouses and employ some 150,000 workers, producing €7.2 billion [58] worth of vegetables, fruit, plants, and flowers, some 80% of which is exported.
Mold growth can be inhibited by keeping surfaces at conditions that are further from condensation, with relative humidity levels below 75%. This usually translates to a relative humidity of indoor air below 60%, in agreement with the guidelines for thermal comfort that recommend a relative humidity between 40 and 60 %.
Equilibrium moisture content of wood versus humidity and temperature, according to the Hailwood-Horrobin equation. The equilibrium moisture content (EMC) of a hygroscopic material surrounded at least partially by air is the moisture content at which the material is neither gaining nor losing moisture.
The heat index (HI) is an index that combines air temperature and relative humidity, in shaded areas, to posit a human-perceived equivalent temperature, as how hot it would feel if the humidity were some other value in the shade. For example, when the temperature is 32 °C (90 °F) with 70% relative humidity, the heat index is 41 °C (106 °F ...