Ice-Nine

Dr. Bernard Vonnegut (1914-1997), Kurt Vonnegut, Jr.'s brother, was a professor of atmospheric sciences at the State University of New York at Albany, retired in 1985. A colleague of Dr. Vonnegut, Vincent J. Schaefer, discovered in an experiment during the 1940s that dry ice rapidly produced ice crystals when introduced into a cloud of supercooled water droplets.

Many clouds in our atmosphere are giant collections of supercooled water droplets that refuse to precipitate. One form that clouds precipitate is by a process called aggregation where the water droplets freeze and begin to fall through the cloud, gaining mass as they contact and acquire other water droplets on their way down. Unfortunately, water in this form will not freeze without the help of a condensation nuclei or until the temperature reaches levels around or below -40°C (-40°F), hence the designation "supercooled".

The dry ice (solid carbon dioxide) Schaefer introduced into the cloud acted as a cooling agent, instantly bringing the droplets well past the necessary -40°C (-40°F) they need to freeze causing the cloud to precipitate. This was the birth of cloud seeding, or the artificial coaxing of precipitation by introducing particles into clouds to act as condensation nuclei and/or a cooling agent.

Dr. Vonnegut soon discovered that silver iodide has a crystalline structure similar to an ice crystal and that, because of this, it acts as an effective ice nucleus at temperatures of only -4°C (25°F). Additionally, silver iodide is far easier to handle than dry ice when attempting to fly it over a cloud to seed the cloud, which is precisely a process that Dr. Vonnegut refined and that is still in use by rainmaking corporations today.

It was this process and research of cloud seeding that inspired his brother Kurt Jr. to create and write a wonderful novel about Ice-Nine.

(some people used to spell it "Ice-9")

'There are several ways,' Dr Breed said to me, 'in which certain liquids can crystallize - can freeze - several ways in which their atoms can stack and lock in an orderly, rigid way.'

'Now suppose,' chortled Dr Breed, enjoying himself, 'that there were many possible ways in which water could crystallize, could freeze. Suppose that the sort of ice we skate upon and put into highballs - what we might call ice-one - is only one of the several types of ice.

Suppose water always froze as ice-one on Earth because it had never had a seed to teach it how to form ice-two, ice-three, ice-four.... ? And suppose,' he rapped on his desk with his old hand again, 'that there were one form, which we will call ice-nine - a crystal as hard as this desk - with a melting point of, let us say, one hundred degrees Fahrenheit, or, better still, a melting point of one hundred and thirty degrees.'

He raised a finger and winked at me. 'But suppose... a Marine threw that seed into the nearest puddle....?'
'The puddle would freeze?' I guessed.
'And all the muck around the puddle?'
'It would freeze?'
'And all the puddles in the frozen muck?'
'They would freeze?'
'And the pools and the streams in the frozen muck?'
'They would freeze?'
'You bet they would!' he cried. 'And the United States Marines would rise from the swamp and march on!'

Cats Cradle - Kurt Vonnegut