Hard to know without examining the underlying source code between the two. There are multiple equations (they are estimates only and for specific use cases) along with multiple variables that may or may not be accounted for. Differential leaf temperature for example.
See this thread for some detail:
I’ve made several updates to the temperature conversion classes:
Added Rankine units.
Set the base class to Celcius such that any mathematical operations using the temperature types are always performed in Celcius and then converted back to the target temperature unit. Math with temperature, in some cases, is nonsensical since we should be talking temperature deltas. Though, as a class, mathematical formulas can utilize the conversions allowing for flexibility. Just be aware that additions be…
And, this post in particular:
There are several VPD algorithms that are essentially estimations applicable to specific circumstances. Here are a couple that are most applicable (with reasonable error) for the temperature ranges we’d typically consider. It’s been awhile since I looked at this but from what I recall, three steps, here:
Saturation pressure (aka partial pressure of water)
Vapor pressure
Vapor pressure deficit
(1) Saturation pressure
These calculate the “saturation pressure”:
Goff Gratch (1984):
[image]
whe…
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