I have three values with wind direction at differrent altitudes.
A1: 020, A2: 2000 feet,
B1: 010, B2: 5000 feet,
C1: 350, C2: 10000 feet
and I would like to forecast the wind direction for D2: 3000 feet. I’ve tried the forecast function but it goes haywire with the change from 010 to 350 degrees.
I made an assumption and I don’t know if it’s valid. I assume that all three wind directions will be within 180 degrees of each other. That is, if the wind is 090 at 2,000 feet, it won’t be 270 at 5,000 feet. If it is, you probably don’t want to be flying in it anyway. If that assumption holds, here’s what I came up with:
Note that that’s an array formula entered with Control+Shift+Enter, not just Enter.
If I have a range of wind directions that crosses zero (left), I shift it 180 degrees (right), do that deed, and shift it back. First I determine if the difference between the MIN and MAX is more than 180. Since I’m assuming that no three wind directions will be more than 180, if they are they must cross zero. For those that don’t cross zero, it’s a pretty straight forward FORECAST formula,
If they do cross zero, there’s a little more work to be done. To rotate them around 180 degrees, I use the MOD function on the x-axis argument,
Then I rotate that result around 180 degrees again using the same method.