Humidity variables review

1.  


Mixing ratio has units of grams per kilogram (g/kg)

Here's another question (and answer) from last week's in-class optional assignment


The mixing ratio only changes value when you add or remove water vapor.


If you cool the air enough you can cause water vapor to start to condense.  The air is losing water vapor, the amount of water vapor in the air is decreasing.  Mixing ratio will decrease in that case.

2.


Saturation mixing ratio also has units of grams/kilogram. 


You can look the value of saturation mixing ratio up in a chart (like the one of p. 84 in the ClassNotes)

Here are a few more questions from last week's optional assignment

We'll work some humidity example problems.  This is the way to become more familiar with the humidity variables:  how they behave and what causes them to change value.  We'll make use of the table of saturation mixing ratios on p. 84 and the charts on pps 85 & 86 in the ClassNotes. 

3.


The relative humidity really doesn't tell you how much water vapor is actually in the air.




4.
The dew point temperature has a couple of jobs.  Here's the one we'll be using today


Cooling air doesn't change the mixing ratio.  As you cool air the saturation mixing ratio decreases.  Eventually the values of the mixing ratio and saturation mixing ratio become equal and the RH becomes 100%.

This is the dew point's other job.  One of the example problems will try to show that if you know the dew point temperature you can easily figure out the mixing ratio and vice versa.