Most people are comfortable with a dew-point temperature of 60 degrees Fahrenheit (16 degrees Celsius) or lower. At a higher dew point of, for example, 70 F (21 C), most people feel hot or “sticky” because the amount of water vapor in the air slows the evaporation of perspiration and keeps the body from cooling.

Dew point pressure is defined as the pressure at which the first droplet of liquid appears at a specific temperature. The phase envelope for a typical gas condensate shows that the dew point pressure is a function of the temperature.

1. DEWPOINT AND VAPOR PRESSURE DEFICIT EQUATIONS.
2. Dew point temperature = Tdew = (237.3*X) / (17.269-X)
3. Vapor Pressure Deficit = es-ea = es-(Rh*es/100) at any instant.

The dew point is the temperature the air needs to be cooled to (at constant pressure) in order to achieve a relative humidity (RH) of 100%. The higher the dew point rises, the greater the amount of moisture in the air. This directly affects how “comfortable” it will feel outside.

Changing the pressure affects the vapor pressure and therefore the temperature at which saturation occurs. Thus, the dew point temperature is determined by keeping the pressure fixed. Changes in pressure slightly modify the dew point temperature.

Dew point can be calculated using the air temperature and a relative humidity value, which is measured using something called a sling psychrometer. A psychrometer is a metal rod, around 6 inches long, that has a thermometer attached at the top.

Pressure changes affect dew point, not temperature changes. As pressure rises, the dew point increases and as pressure decreases dew point temperature also decreases.

A dew point between 55°F and 60°F is noticeably humid. It’s muggy when the dew point is above 60°F, and it’s uncomfortable outside when it ticks above 65°F. Any dew point readings above 70°F are oppressive and even dangerous, the kind of stickiness you experience in the tropics or during a brutal summer heat wave.

Although it is easy to confuse one for the other, the measured pressure dew point of compressed air and the atmospheric dew point, are two distinct entities. For more clarity, the pressure dew point is measured within a compressed air system while the atmospheric dew point refers to a naturally occurring physical phenomenon.

Dew Point. Dew Point is the temperature below which the moisture in the air becomes water droplets and forms dew. The temperature changes based on the relative humidity, temperature & pressure of atmosphere. The ideal dewpoint temperature is anywhere between -4.5° C to 15.5° C to avoid discomfort of human beings, however,…

The dew point is calculated according to the following formula: Ts = (b * α(T,RH)) / (a – α(T,RH)) where: Ts is the dew point; T is the temperature; RH is the relative humidity of the air; a and b are coefficients.

The higher the dewpoint is, the more moisture that is in the air. The higher the dewpoint is above 65 F, the stickier it will feel outside (feels like you have to breathe in a bunch of moisture with each breath). 75 F or above dewpoint, the air really feels sticky and humid. RH can be more difficult to explain.