Looking at the table, 7.984 mb is somewhere between 7.580 (a temperature of 3 o Celsius) and 8.135 (a temperature of 4 o Celsius). Using the lookup table below the calculator, we need to determine the temperature which corresponds the closest to the actual vapor pressure, in this case a vapor pressure of 7.984 mb.
Once we have this value, we can forecast the current temperature dewpoint in degrees Celsius. What is the actual vapor pressure, given that the atmosphere is only at 65% of its capacity? The calculator provides a value of 7.984 mb of pressure. The vapor pressure of a saturated atmosphere at the given temperature calculates (click on the "Evaluate" button) to 12.283 mb of pressure. Once we have calculated the SVP, we can adjust it for an atmosphere that is less than completely saturated:Īctual vapor pressure (VP) = SVP x RH / 100įor example, in the calculator below, the input values are 10.0 o Celsius with a relative humidity of 65%. Values may be obtained from Table 3 or calculated from the following formulas (Hyland and Wexler 1983b).
#Saturation humidity ratio calculator series
Given these two values, how might one "forecast" a temperature dewpoint? A series of algorithms, or calculations, can be performed to determine the vapor pressure of water (in millibars, or mb) if the atmosphere is saturated (i.e, if the relative humidity is 100%) or the actual vapor pressure if the atmosphere is not completely saturated. The water vapor saturation pressure is required to determine a number of moist air properties, principally the saturation humidity ratio. Surface temperature (in degrees Celsius).The Relative Humidity (RH) is the ratio of the actual water vapour. In this calculator, it is assumed that one can measure (using simple meteorological measuring devices such as might be found at any home improvement store) two values: The svp below freezing can be corrected after using the equation above, thus. Saturation Mixing Ratio Saturation Mixing Ratio Calculator Introduction : this calculator is used to demonstrate how one might use a mathematical model to "forecast" a meteorological variable, in this case a temperature dewpoint.