Planting trees is a popular strategy for fighting the warming temperatures caused by climate change. That’s because forests pull carbon dioxide (CO2), a heat-trapping greenhouse gas, out of the atmosphere. Now, scientists from Princeton University in New Jersey are investigating another way forests may help cool the planet: cloud formation.

Low-lying clouds are often spotted over forests. That’s because trees release water vapor into the air during photosynthesis—the process by which plants harness the sun’s energy to make food. This vapor can help form clouds. Since clouds are white—a color that reflects the sun’s rays—researchers think that the cloud cover over forests can help prevent heat from reaching Earth, further cooling the ground below.