"Experimental physicists growing icicles are closer to understanding why some form with ripples up and down their outsides, while others form with smooth, slick, even surfaces. By growing icicles from water samples with different contaminants like sodium chloride (salt), dextrose (sugar) and fluorescent dye, they discovered that water impurities become entrapped within icicles as they form and subsequently create chevron patterns that contribute to a ripple effect around their circumferences."