As we all know the wind can have a tremendous affect on the trajectory of your bullet or pellet towards the target. You may well be centred precisely on the centre spot, your natural point of aim as good as it has ever been and your pulling of the trigger imperceptible BUT once the projectile leaves the barrel you are at the mercy of the wind (well and gravity).
Outside the circle are numbers in coloured circles. The numbers represent the hours of the clock face. Outside the coloured circles are purple arrows pointing into the clock face to represent different possible winds directions from where the wind can blow.
A wind from 12 o’clock is blowing straight at you whereas a wind from six o’clock is blowing from directly behind you. On the right hand side of the clock face the winds blow from the right etc.
The inside of the circle is the representation of your target and where the fall of shot occurs.
Each little circle inside the circle is the same colour as one of the hour points on the clock face and shows where the shot will fall, if uncorrected.
So with the wind coming from 10pm and 11pm the shots will be pushed low and right on the target down towards 5pm on the clock face.
A shot fired into a headwind from 12 o’clock will fall high on the target deflected slightly to the right due to the spin of the bullet as barrel rifling makes the bullet rotate clockwise. This principle applies to all shots due to the rotation of the bullet in flight.
Finally there are 6 little boxes with percentage numbers in them. A crosswind at 90 degrees to the bullet flight is stronger than a wind blowing diagonally at 45 degrees to the bullet flight and such a 45 degree wind is roughly half the strength of a 90 degree crosswind. Clearly the nearer the wind is to a headwind or tailwind the less strength it has compared to a pure 90 degree crosswind.