Ancient Hindus and Bhuddists believed that elephants are the spiritual cousins of clouds and possess the power to encourage the clouds to form and bring rain. We have always thought that this is why so many people seem to see elephant-shaped clouds.
However, scientists at the Georgia Institute of Technology have found evidence to suggest that, rather than elephants, it is microscopic phytoplankton that actually posses the power to bring clouds. They found that increases in cloud cover over the Southern Ocean, around Antarctica, corresponded to a large bloom in the population of the sea organisms. It seems that the phytoplankton emit chemicals which find their way up into the atmosphere and act as microscopic nuclei onto which the cloud droplets can form.
If you want to know more:
Plankton: The New Cousins of Clouds
November 20, 2006