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0006380Dwarf FortressDwarf Mode -- Buildings, Machinespublic2013-10-02 13:572014-08-01 11:08
Toady One 
normalminorhave not tried
0006380: Wind strength constant on smaller worlds?
Little proper information is available on the behavior of windmills in Dwarf Fortress, so I attempted to analyze the code behind determining wind strength and found what appears to be a bug.

When wind strength is calculated, it first determines X/Y strength based on the current time of day (and based on region properties), then it further adjusts the Y strength based on your latitude. The latitude variance has special cases for each world height (17, 33, 65, 129, and 257) to scale them to the range of 0-256, but if the world height is found to be less than 129 (i.e. any POCKET, SMALLER, or SMALL worlds), it simply ignores the latitude and uses a static wind strength of 3 (instead of varying values between -20 and +25).
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Issue History
2013-10-02 13:57QuietustNew Issue
2013-10-02 14:36QuietustNote Added: 0024152
2013-10-21 10:17QuietustNote Added: 0024170
2014-03-19 17:40FootkerchiefTag Attached: Fixed in 0.34.12?
2014-05-22 12:35QuietustNote Edited: 0024152bug_revision_view_page.php?bugnote_id=0024152#r9266
2014-07-07 22:23FootkerchiefTag RenamedFixed in 0.34.12? => Fixed in 0.40.01?
2014-08-01 06:03QuietustNote Added: 0028078
2014-08-01 11:08DwarfuNote Added: 0028086
2014-08-01 11:08DwarfuStatusnew => resolved
2014-08-01 11:08DwarfuFixed in Version => 0.40.05
2014-08-01 11:08DwarfuResolutionopen => fixed
2014-08-01 11:08DwarfuAssigned To => Toady One
2014-08-01 11:08DwarfuTag Detached: Fixed in 0.40.01?

2013-10-02 14:36   
(edited on: 2014-05-22 12:35)
Doing some further examining, I've tested several worlds and have been unable to locate any regions which have morning/evening winds - it's possible that although windmills contain logic to handle them, the game never actually generates them in the world to begin with (or they're generated dynamically during gameplay, and I was only analyzing them after worldgen).

2013-10-21 10:17   
The logic for scaling latitude to fit the 0-256 range appears to have been added in version 0.31 (with the same problem for small worlds), as it was not present in
2014-08-01 06:03   
This appears to be fixed in version 0.40.05 - the wind strength function no longer has a special case for height<129.
2014-08-01 11:08   
Thanks for the update!