Palm Springs Windmills

Touring Palm Springs' collection of windmill farms, we learned that modern windmills turn to face the wind and that there are five reasons that a windmill surrounded by turning windmills might itself not be turning:

1. Routine maintenance
2. It hasn't reached its minimum start up speed
3. It has reached its maximum speed and has switched off to avoid flying apart
4. It is obsolete and is being cannibalized for parts
5. The windmill is undergoing tests before it goes on-line

I forgot to ask why white is the default color for windmills.