1. Review Moist virtual effect
Tv: the temperature that dry air would need to have at the given pressure in
order to have the same density as moist air, assuming idea gas behavior.
If it’s saturated,
rl is the liquid water mixing ratio

2. Calculate air density
Example
p=1010.5hPa, T=300.2K, h=98.0%

3. Estimating Errors of derived variables/Propagation of Errors
Consider a quantity
where A, B, C are measured quantities,
The error associated with each of them is
What is the error of the derived variable X? .
Max error:

4. Applied to air density .
Max error: