(Top) a plot of α _s , the inclination needed to dislodge a drop of water, is plotted against the volume Ω of the drop, put on a plane of acrylic. Dashed lines indicate limits for definition of α _s , which cannot exceed 90° (in this case the drop will not fall under its weight). Thus for volumes on the left of the vertical dashed line, α _s is not defined. (Middle) a plot of us, the minimum wind speed needed to dislodge a drop, is plotted against the diameter D of the drop lying on a plane of acrylic. (Bottom) the direction, taken by a drop of volume  put on a vertical plane in front of a blower, is plotted against the speed u of the wind. Two values of the volume are used (blue dots: 20 µl, and green crosses: 25 µl).