As moisture evaporates from the leaves, water has to be pulled up from the roots and delivered to the top of the tree, working against gravity.
ففيما تتبخر الرطوبة من الاوراق ،‏ يُسحب الماء من الجذور ويصل الى رأس الشجرة ،‏ مقاوِما قوة الجاذبية .‏