Good day! I found the definition of dew point and frost point somewhat odd on wikipedia.
At the first line you see
The dew point is the temperature to which air must be cooled to become saturated with water vapor.
It's okay.
But further frost point is defined as
When the temperature is below the freezing point of water, the dew point is called the frost point, as frost is formed via deposition rather than condensation to form dew.
Do I understand correctly that they are talking about the dew point temperature (which called frost point if it is below zero, regardless of the current real gas temperature), not about the real temperature of the gas at which this dew point is measured?
In any case, I think this definition is not entirely correct, because the dew point is below frost point when the value is below zero. Am I right?
At the end of the article, there is another definition that contradicts the previous one:
The frost point is similar to the dew point in that it is the temperature to which a given parcel of humid air must be cooled, at constant atmospheric pressure, for water vapor to be deposited on a surface as ice crystals without undergoing the liquid phase (compare with sublimation). The frost point for a given parcel of air is always higher than the dew point, as breaking the stronger bonding between water molecules on the surface of ice compared to the surface of liquid water requires a higher temperature.
This is more correct, right? Is it necessary to edit the article, or in fact these two definitions do not contradict each other (and why, if so)?
Some other people can confuse these concepts. There is a number of dew point/humidity calculators, for example: Michell Humidity Calculator (this is one of the manufacturers of dew point sensors). This calculator strongly suggests me to replace the dew point with the dew point/frost point known parameter when I want to calculate the humidity for a dew point of -40. Should I nevertheless use the known dew point value in the calculation? When I use their sensors, do they mean dew point if their measuring range contains negative values (for example: dew point measurement range from -100 °C to 20 °C)? Is it always we are talking about a negative dew point (and not about a frost point), unless otherwise stated?
