You may want to think twice before you let snow drops fall on your tongue the next you're out in the snow.

Scientists have known for over 40 years that ice crystals in clouds, which become rain or snow, need to cling to some kind of particle, called ice nucleators, in order to form in temperatures above minus 40 degrees Celsius.

Scientists have known for about forty years that bacteria cling to ice high in the atmosphere in order to produce rain and snow.

However, U.S. scientists only recently found out that biological organisms, such as bacteria and other such microorganisms, play a significant role in the formation and distribution of precipitation.

Bacteria are by far the most active ice nuclei in nature, said Brent C. Christner, an assistant professor of biological sciences at Louisiana State University.

The most common bacteria found was Psedomonas syringae, which can cause disease in several types of plants including tomatoes, green beams and other similar plants.

The bacterium was found in 20 samples of snow from around the world and the study showed that the most bacteria-rich snow came from France, followed by Montana and the Yukon. It was even found in snow from Antarctica while subsequent research has also found it in summer rainfall in Louisiana.