Thanks to all, i doesn't seen the settings menu yet...
Merci idefix, tu parles mieux anglais que moi :-) a+
I think the color gradient used isn't very clear and the scale too low (excuse for my english, i'm not english). You go from blue for low speed to blue for high speed
For example this gradient must be better (in km/h), we see with this that high wind speed is in red and red darker for very high speed.