During the late afternoon an air temperature of +12°C and a dew point of +5°C were measured. What temperature change must at least occur during the night in order to induce saturation ?
DEW POINT TEMPERATURE
The dew point is the temperature the air needs to be cooled to (at constant pressure) in order to achieve saturation (= a relative humidity (RH) of 100%). In simple words, it is the temperature at which the air can no longer "hold" all of the water vapour which is mixed with it - and some of the water vapour must condense into liquid water.
- The dew point is always lower than (or equal to) the air temperature => If the air temperature cools to the dew point, or if the dew point rises to equal the air temperature, then dew, fog or clouds begin to form. At this point where the dew point temperature equals the air temperature, the relative humidity is 100%.
=> In this case, Temp. = +12°C; DP = +5°C; Saturation occurs when the air temperature = dew point.
Dew point +5ºC = is the temperature to which the air must be cooled in order for saturation to occur.
Your Notes (not visible to others)
This question has appeared on the real examination, you can find the related countries below.
-
Czech Republic1
Use Keyboard Shortcuts
Use your keyboard for faster navigation
