It’s Raining … Bacteria?

A few days ago, I was browsing the Internet when I came across an article stating that several common species of bacteria were discovered in hailstones that fell from near by storm clouds in the atmosphere. This is fascinating for me because it counters my previous assumption that most bacteria are land bound, and those that exist in the atmosphere, existed at low altitudes. I’ve always assumed that the higher the altitude, the more extreme the environment it is for bacteria to survive.

The article stated that a group of researchers in Denmark analyzed hailstones from 2009 and found that it contained, “several species of bacteria that tended to reside on plants, as well as thousands of organic compounds normally found in soil.” (Ghose, 2013) The discovery of microorganism life in clouds is revolutionary because it use to be difficult to study since rain was easily contaminated when it falls from the sky. Hail, however, freezes the microorganisms on the inside, making it easy to study just by sterilizing the outer, contaminated layers. (Rumaithi, 2013). In fact, the hailstones not only contained several species of bacteria typically found in plants and soil, but also thousands of organic, carbon compounds, the same number compounds found in a typical river. (Ghose, 2013). The researchers explained that some of the bacteria are able to act as bases for ice crystals to attach to in the storm clouds. When enough ice crystals have attached to the bacteria, they will fall as either rain or snow, depending on the temperature. (Ghose, 2013) In addition, researchers also found that the bacteria are able to produce a pinkish pigment that will allow the bacteria to adapt to the high energy and high frequency of the ultraviolet (UV) rays in the atmosphere (Ghose, 2013). In fact, the Bactillus Subtilis, a common strand of bacteria commonly found in soil, possess, dark-red pigments, which are 10 times more resistant to UV rays. (Moeller, R., Horneck , G., Facius, R., Stackebrandt, E., 2005)(Wikipedia, n.d.) The pigment protects the bacteria from UV ray by preventing a dangerous reaction between two molecules of thymine, an important base in the structure of DNA. (Rammelsberg, 1998)

Picture 1: A picture of hailstones.

To understand how bacteria can be found in the storm clouds, it must first be understood how the storm clouds are formed. The storm clouds, known as cumulonimbus clouds, have temperatures below 0˚C and are known for “producing lightning and other dangerous severe weather, such as gusts and hail”, (Wikipedia, n.d.) When the cumulonimbus clouds are formed, the hotter air with the lower density, since the molecules will be more spread out, will be pushed (by density laws) upwards by the denser, colder air wedging underneath, creating an upward force (Ophardt, 2003). Researchers theorized that the bacteria from nearby ecosystems would be swept into the cumulonimbus clouds by the updraft force, where it would be attached by ice. (Ghose, 2013)

Picture 2: A picture of a cumulonimbus cloud

The discovery of microorganisms in the Earth’s atmosphere can open multiple possibilities and theories. For example, researchers suggest that this discovery can create the theory that, “ bacteria could influence weather patterns. They may be growing in clouds, increasing in number and then not only modifying the chemistry in the clouds but also in the atmosphere indirectly.” (Ghose, 2013). I believe that this means that if bacteria were found to be responsible for weather pattern, the weather can be predetermined and manipulated by changing the growth of bacteria in the atmosphere. Secondly, the discovery of bacteria in the cumulonimbus clouds shows that bacteria can survive in extreme cold temperatures. It raises a question for myself about how effective is cold temperature at preventing the growth of bacteria. It shows that keeping the bacteria in freezing temperatures may not be the most effective way the inhibiting bacterial growth. Clearly, there is still so much about bacteria and their roles on our everyday life that we do not know about.

Assorted Hail Stones. [Photography]. Retrieved from Encyclopædia Britannica Image Quest.

Cumulonimbus Storm Cloud Seen From Below. [Photography]. Retrieved from Encyclopædia Britannica Image Quest.

Ghose, T. (2013, January 23). Storm Clouds Crawling With Bacteria. Live Science.
Retrieved January 23rd, 2013, from

Moeller, R., Horneck , G., Facius, R., Stackebrandt, E. (2005, January 1). Role of Pigmentation in Protecting Bacillus sp. Endospores Against Environmental UV Radiation. US National Library of Medicine National Institutes of Health. Retrieved January 25, 2013, from

Ophardt, C. E. (2003) Density Applications with Gases. Virtual Chebook: Elmhurst College. Retrieved January 26, 2013, from

Rammelsberg, A. (1998, August 17). How Does Ultraviolet Light Kill Cells?. Scientific
. Retrieved January 25, 2013, from

Rumaithi, S. A. (2013, January 25), Microbial Life Survives in Storm Clouds. Top News. Retrieved January 25, 2013 from

Wikipedia. (n.d.). Bactillus Subtilis. Wikipedia. Retrieved January 25, 2013, from

Wikipedia. (n.d.). Cumulonibus Cloud. Wikipedia. Retrieved January 25, 2013, from

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