Can someone tell me how practical it would be to create a realistic moving field, in the hope of getting wind speed data represented on the grass ??

I am very new to this so have no idea whether this is practical or not, thanks

This problem really depends on how fancy you want to get.

The simplest solution would treat each blade of grass as a single vertical line. For low wind speeds, you could have the line tilt at an angle (with respect to the vertical) proportional to the wind speed, and pointing in the direction of the wind. This should be pretty easy to implement.

This fails, of course, at high wind speeds, where the response should become non-linear - with the linear response, the grass will be horizontal at some finite wind, and below the plane at some higher speed. You could use a simple function to approximate this - you'd need something that is nearly linear at small speeds, but approaches a constant (90deg) as the wind speed approaches infinity. I think a tan function might work.

If you want to get really fancy, you'd treat the grass not as a straight line but as a curve. In this case, you'd want to look at the physics of cantelievers. These are like springs, but respond to an applied force by bending, rather than stretching or compressing. The easiest solution would be to treat the winds as acting only on the tip of the blade. The most realistic would be to treat the blade as a full physical body, where the wind acts on every part. This is probably going overboard.

Good luck!