[TriLUG] OT: the difference between web bulb and dew point temperatures

[John Vaughters via TriLUG]

  Joe,
Let me elaborate a little bit more and this goes back to my thermodynamics professor from many years back. Basically the Dew Point is what you want to know for various reasons, like what temperature will it be in the morning and will it freeze and kill my crops, or a pilot trying to be wary of water condensing and freezing on his carburettor and sending him on an unexpected trip back to the ground as well as many other reasons. So the goal is to find the Dew Point Temp. How do you do that? The direct temp measure with human observation of condensation is not very convenient and unreliable, so other methods, historically the wet bulb measurement, can help you calculate the dew point. So the relationship was born out of need to know the Dew Point Temp. and the wet bulb was a convenient method for calculation. In more modern times we rely on Relative Humidity sensors, but back in the day, putting a wet sock on the bulb and swinging in the air from a string was actually the appropriate way to measure the wet bulb. Understanding the history of physical measurements can be helpful in understanding why this wet bulb data point even exists.
I hope that helps.
John Vaughters