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The representation is made on a temperature-relative humidity, instead of a standard psychrometric chart. The comfort zone in blue represents the 90% of acceptability, which means the conditions between -0.5 and +0.5 PMV, or PPD < 10%.
K) specific gas constant for dry air ρa = P_a / (Rs_a * Tair) return ρa end # Wet air density ρ [kg/m3] # Tair air temperature in [Kelvin] # P absolute atmospheric pressure [Pa] function wet_air_density (RH, Tair, P) es = water_vapor_saturated_pressure (Tair, P) e = es * RH / 100 ρv = water_vapor_density (e, Tair) ρa = dry_air_density (P-e ...
NIR absorption bands are typically 10–100 times weaker than the corresponding fundamental mid-IR absorption band.) [4] The lower absorption allows NIR radiation to penetrate much further into a sample than mid infrared radiation. Near-infrared spectroscopy is, therefore, not a particularly sensitive technique, but it can be very useful in ...
To compute the VPD, [2] we need the ambient (greenhouse) air temperature, the relative humidity and, if possible, the canopy air temperature. We must then compute the saturation pressure. Saturation pressure can be looked up in a psychrometric chart or derived from the Arrhenius equation; a way to compute it directly from temperature is
The precipitable water can also be calculated by integration of radiosonde data (relative humidity, pressure and temperature) over the whole atmosphere. Data can be viewed on a Lifted-K index. The numbers represent inches of water as mentioned above for a geographical location. Recently, methods using the Global Positioning System have been ...
Atmospheric thermodynamics is the study of heat-to-work transformations (and their reverse) that take place in the Earth's atmosphere and manifest as weather or climate. . Atmospheric thermodynamics use the laws of classical thermodynamics, to describe and explain such phenomena as the properties of moist air, the formation of clouds, atmospheric convection, boundary layer meteorology, and ...
Determining the effect of temperature change on relative humidity: For air of a fixed water composition or moisture ratio, find the starting relative humidity from the intersection of the wet and dry bulb temperature lines. Using the conditions from the previous example, the relative humidity at a different dry bulb temperatures can be found ...
e * is the saturation water vapor pressure T is the absolute air temperature in kelvins T st is the steam-point (i.e. boiling point at 1 atm.) temperature (373.15 K) e * st is e * at the steam-point pressure (1 atm = 1013.25 hPa) Similarly, the correlation for the saturation water vapor pressure over ice is: