Rain, snow forms with aid of living organisms: study

February 28, 2008
Ice-nucleating Bacteria
Cells of ice nucleating bacteria (green dots) entrapped in ice crystals. Credit: Brent Christner

Brent Christner, LSU professor of biological sciences, in partnership with colleagues in Montana and France, recently found evidence that rain-making bacteria are widely distributed in the atmosphere. These biological particles could factor heavily into the precipitation cycle, affecting climate, agricultural productivity and even global warming. Christner and his colleagues will publish their results in the prestigious journal Science on Feb. 29.

Christner’s team examined precipitation from global locations and demonstrated that the most active ice nuclei – a substrate that enhances the formation of ice – are biological in origin. This is important because the formation of ice in clouds is required for snow and most rainfall. Dust and soot particles can serve as ice nuclei, but biological ice nuclei are capable of catalyzing freezing at much warmer temperatures. If present in clouds, biological ice nuclei may affect the processes that trigger precipitation.

The concept of rain-making bacteria isn’t far-fetched. Cloud seeding with silver iodide or dry ice has been done for more than 60 years. Many ski resorts use a commercially available freeze-dried preparation of ice-nucleating bacteria to make snow when the temperature is just a few degrees below freezing.

“My colleague David Sands from Montana State University proposed the concept of ‘bioprecipitation’ over 25 years ago and few scientists took it seriously, but evidence is beginning to accumulate that supports this idea,” said Christner.

But, what makes this research more complicated is that most known ice-nucleating bacteria are plant pathogens. These pathogens, which are basically germs, can cause freezing injury in plants, resulting in devastating economic effects on agricultural crop yields.

“As is often the case with bacterial pathogens, other phases of their life cycle are frequently ignored because of the focused interest in their role in plant or animal health,” said Christner. “Transport through the atmosphere is a very efficient dissemination strategy, so the ability of a pathogen to affect its precipitation from the atmosphere would be advantageous in finding new hosts.”

It is possible that the atmosphere represents one facet of the infection cycle, whereby the bacteria infects a plant, multiplies, is aerosolized into the atmosphere and then delivered to a new plant through atmospheric precipitation.

“The role that biological particles play in atmospheric processes has been largely overlooked. However, we have found biological ice nuclei in precipitation samples from Antarctica to Louisiana – they’re ubiquitous. Our results provide an impetus for atmospheric scientists to start thinking about the role these particles play in precipitation,” said Christner. “This work is truly multi-disciplinary, bridging the disciplines of ecology, microbiology, plant pathology and climatology. It represents a completely new avenue of research and clearly demonstrates that we are just beginning to understand the intricate interplay between the planet’s climate and biosphere.”

Source: Louisiana State University

Explore further: First quantifiable observation of cloud seeding

Related Stories

First quantifiable observation of cloud seeding

January 23, 2018

A University of Wyoming researcher contributed to a paper that demonstrated, for the first time, direct observation of cloud seeding—from the growth of the ice crystals through the processes that occur in the clouds to ...

Why thawing permafrost matters

January 12, 2018

In Bethel, Alaska, walls are splitting, houses are collapsing, and the main road looks like a kiddy rollercoaster. In the coastal town of Kongiganak, sinking cemeteries prevent Alaskans from burying their dead in the ground. ...

The Greenland ice sheet contains nutrients from precipitation

November 4, 2015

New research shows that the ice sheet on Greenland contains the nutrient phosphorus, which was carried by the atmosphere across the country, where it fell with precipitation. Studies of the ice core drilling through the kilometers-thick ...

Recommended for you

Hauling antiprotons around in a van

February 22, 2018

A team of researchers working on the antiProton Unstable Matter Annihilation (PUMA) project near CERN's particle laboratory, according to a report in Nature, plans to capture a billion antiprotons, put them in a shipping ...

Urban heat island effects depend on a city's layout

February 22, 2018

The arrangement of a city's streets and buildings plays a crucial role in the local urban heat island effect, which causes cities to be hotter than their surroundings, researchers have found. The new finding could provide ...

A statistical look at the probability of future major wars

February 22, 2018

Aaron Clauset, an assistant professor and computer scientist at the University of Colorado, has taken a calculating look at the likelihood of a major war breaking out in the near future. In an article published on the open ...

0 comments

Please sign in to add a comment. Registration is free, and takes less than a minute. Read more

Click here to reset your password.
Sign in to get notified via email when new comments are made.