Water: Cooling or Burning?

By Stephanie Lam
Stephanie Lam
Stephanie Lam
January 11, 2010 Updated: October 1, 2015
Given the right focal point, water droplets can cause leaf burn. (The Epoch Times)
Given the right focal point, water droplets can cause leaf burn. (The Epoch Times)

Water can cause sunburn, researchers led by Dr. Gábor Horváth of Hungary’s Eötvös University found. They investigated different conditions’ effects on water droplets’ ability to focus sunlight on leaves, thus causing sunburn.

The research, published in New Phytologist last Friday, involved both computational and experimental studies to determine in what conditions would water cause sunburn to a leaf.

“The problem of light focusing by water droplets adhered to plants has never been thoroughly investigated, neither theoretically, nor experimentally,” said Horváth in a press release. “However, this is far from a trivial question. The prevailing opinion is that forest fires can be sparked by intense sunlight focused by water drops on dried-out vegetation.”

Horváth and his colleages found that water droplets do not burn maple or ginkgo leaves because their surfaces are smooth. However, floating fern leaves are susceptible to leaf burn because water droplets can land on top of the leaves’ wax hairs, thus acting as a magnifying glass on top of the leaves.

“The same phenomenon can occur when water drops are held above human skin by body hair,” the researchers wrote in the paper. “However, sustained exposure of a given patch of skin to intense focused sunlight would require that the sun-bathing person’s position remains constant relative to the sun; otherwise, the water drops receive sunlight from a continuously changing direction, and focus it onto different skin areas. Therefore, we treat claims of sunburn due to water droplets on the skin with a healthy dose of skepticism.”

Theoretically, the researchers wrote, if water droplets’s focal regions fall on a dry plant’s surface, intensely focused sunlight could start a fire. However, it is likely that the water droplets would evaporate before this happens, so the threat is very small.

To read the research paper, please visit http://littleurl.net/cf6cf0

Stephanie Lam
Stephanie Lam