Nature’s Cooler!

A free resting area where you can cool down

　　　Have you ever noticed that it feels cooler to sit in the shade of a tree than in the shade of a building? The reason has to do with how plants manage to survive hot summers through two processes called 'transpiration' and 'convection. 

　　　What is transpiration? Transpiration is where plants absorb water through the roots, move it up through the stems, and release it from the leaves as vapor. The water exits the plant through small holes under the plant’s leaves called stomata.  That process causes the air around the tree to cool down and is called “evaporative cooling”. While plants also release some water through photosynthesis, healthy trees actually release around 100 times more water during transpiration than photosynthesis. 

　　　What is convection? When the air cools down near trees, warmer air rises and cooler air flows in, creating a natural circulation known as convection.This process lowers the temperature around the tree, causing the shade to feel even cooler.

　　　Natural cooling effects like transpiration and convection are becoming increasingly important for making cities more comfortable and reducing the heat island effect. The heat island effect is when urban areas become hotter and hotter because there are more people and more buildings, causing the area’s temperature to increase. It shows just how incredible plants are, not just for keeping us cool but also for cooling entire urban areas. Without realizing it, we all benefit from the amazing abilities of plants!