A new study reveals that it is very likely that most of the snowflakes are formed around bacteria which act as cloud condensation nuclei (CCN). This means that the bacteria, as most particles of biological origin, attract water and are surfaces on which moisture condensates to form droplets.

"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 and lead author of the study, quoted by AP.

The research was released Thursday by the journal Science. Scientists analyzed snow samples from all over the world. They found a stronger presence of bacteria in snow collected from Montana and France than that collected in northern Canada and Antarctica, which is somewhat expected.

"Every snow and ice sample we've looked at, we found biological ice nucleators," he said in an interview with AFP. "Here's a component that has been completely ignored to date."

There are concerns especially to crops. The plant pathogen Pseudomonas syringae was found to lead among bacteria found in snow. It is known to infect wheat, corn and other crops. Other living microbes in the clouds might be perpetuating themselves and spreading when it snows or rains, but further research is needed in this direction.