How to use the Vaisala Humidity Calculator

I make it easy on you.
Check out my figures ( saves you hours of work )

Supersaturation over ice at -40C reached at 67.5RH

Lets try RH 67.4 instead of RH 67.5. Oops, no "Supersaturation over ice" popup window. See also the frost point.

Now one RH point more.

Another test but this time with -55C. Those are the exact figures as shown on my yellow table....

now one RH point less. oops, no "Supersaturation over ice" popup window.

Now one RH point more than shown in my yellow table ...

OK. Now that we have the "Saturation with regards to ice " at any given temperature, cirrus clouds need at least -39C in order to form...
How do we calculate " Supersaturation over ice "?
Lets first have a look at this picture:

150% supersaturation with regards to ice translates in 101% saturation with regards to water.
Under natural conditions. You add human made nuclei delieverd via aircraft and the game changes. See pdf document RH_WMO ....

RH-WMO = RH with regards to water
RH-Standard = RH with regards to ice
Above 100% is "supersaturated"

OK. My RH figures are 0.1 higher because I took the minimum values from the --vaisala humidity calculater from when the popup windows " Supersaturation over ice" appears.

A "supersaturation over ice at -40C of  148.3% ( my fugures would have shown 0.2% more ) would be a saturation over water of 100%
Lets have a look how I calculated the figures in the "Grey Table ". See jpg here....
I use now the figures of the yellow table. For example: at -40C the RH must be 67.5% R ( I know now it's actually 67.4 and I'm 0.1% off but lets ignore this minor detail for the moment )
If saturation over ice at -40 is 67.5% ....
-how much is 140% supersaturation over ice?

See "Grey Table " ....
What about at -55C?
We take the saturation level from the yellow table again:
58.2RH at -55C and multiply it by 1.4
See here:

See yellow table again and the grey table and please go to the online Vaisala humidity calculator yourself

My index page is here
 and please read point 7-10