A new study has shown that water’s freezing point is now even lower. 

Scientists in Texas have managed to reduce the limit of when water (H2O) freezes to -47.2°F (-44°C), down from -36.4°F (-38°C). 

They used droplets approximately two nanometers in diameter, which is about one million times smaller that a snowflake to achieve their record.

The researchers believe that the freezing point tiny water dropslets play a crucial role in animal survival in cold environments.

The rupture of an animal cell by a frozen water droplet can cause cell death.

Understanding the conditions that lead to the formation of ice could also help research in planetary science, such as assessing conditions on other worlds.

Researchers at the University of Houston report water-ice phase transformation down to 2 nm (nanometers) in diameter

University of Houston scientists report that water-ice phase transformations can be achieved down to 2nm in diameter (nanometers).

Researchers put droplets as small as two nanometres in contact with soft interfaces, like gels and lipids. An illustration from the team's research paper shows a nanodroplet surrounded by oil where ice nucleation - the initial process that occurs in the formation of a crystal from a solution - occurs

Droplets of droplets up to two nanometres were placed in contact with soft surfaces such as gels or lipids by researchers. A diagram from the research paper of the team shows how a nanodroplet is surrounded in oil. This illustrates where ice nucleation, which occurs when a solution forms a crystal.


Water is composed of two hydrogen molecules bound together to an oxygenatom.

Due to an uneven distribution of electrons within these molecules, hydrogen atoms assume a slight positive charge, while oxygen atoms have a negligible charge.

This not only gives liquid water some of its unique properties but also influences the crystal structure when it freezes.

Water expands once temperatures fall below the freezing point. This is because the electric charges that are on molecules causes it to form an open lattice structure.

The surface becomes slippery when there is friction and pressure that causes the thin layer of ice on top to melt. 

Previously, any water droplet is known to freeze at any temperature between 32°F and -36.4°F (0°C to -38°C). 

The study authors claim that freezing was impossible below that temperature. University of Houston 

They state that water-ice transformation in nanometres of nanodroplets is a crucial role in nature, including climate change and microphysics of cloud, as well as the survival mechanism for animals in cold environments. 

“The findings give an understanding of different natural phenomena and offer a path for designing superior anti-icing Biomimetics or smooth liquid infused surfaces.   

The transformation of water into ice is one of the great mysteries of science, according to the team, and how and why it happens is the subject of intense scrutiny.

Water actually has some odd characteristics – unlike other liquids, it becomes less dense as it freezes. Blocks of water ice floating on water instead of sinking to bottom is due to this fact. 

When liquid water reaches its freezing point it expands. This is why lakes freeze from the top. 

Amazingly, the smallest nanodroplet of water in which ice can form is only as big as 90 water molecules – a tenth of the size of the smallest virus. 

Droplets that are as small and as fine as two nanometers were placed in contact with soft surfaces such as gels and oils to find out more about how water crystallizes into ice. 

Liquid water expands when it starts to reach its freezing point, which accounts for lakes freezing from the top rather than the bottom. Pictured is ice of the frozen Lake Baikal in Russia

The freezing point of liquid water causes it to expand, which is how lakes can freeze. Pictured is ice of the frozen Lake Baikal in Russia

They found they were able to maintain tiny droplets as liquid down to -47.2°F by putting them in contact with soft surfaces. 

It’s thought the suppression of ice nucleation – the initial process that occurs in the formation of a crystal from a solution – was due to pressure on the droplets from the soft interface. 

‘We found that if a water droplet is in contact with a soft interface, freezing temperature could be significantly lower than hard surfaces,’ said study author Professor Hadi Ghasemi at the University of Houston.

‘Also, a few-nanometre water droplet could avoid freezing down to -44°C if it is in contact with a soft interface.’   

It’s already known that the freezing point of water drops as you apply pressure, explains Dr Christopher S. Baird at West Texas A&M University, who was not involved in the study. 

‘For most liquids, applying pressure raises the temperature at which the liquid freezes to solid,’ he said. 

Each molecule of water contains two atoms of hydrogen (H) joined to a single atom of oxygen (O)

Every molecule of water has two hydrogen atoms (H), joined together to one atom oxygen (O).

“A solid forms when loose and meandering liquid molecules get close enough to form strong bonds that hold them together. 

The pressure applied to a liquid forces the molecules closer together. These molecules can form strong bonds that make them solid, even at higher temperatures than their freezing point. 

Water is unique. When water molecules bond into a solid, crystalline structure, they spread. 

“This is because water molecules are spread out during freezing. This means water can be lowered by applying pressure.  

Water’s anomalies, such as how it freezes, are key to many natural and technological processes. 

The new study could also help climate prediction, cloud conditions, cryopreservation of organs and technologies exposed to icing conditions such as aircraft and wind turbines, the University of Houston team say. 

The study was published in Nature Communications. 


Scientists have created a mysterious phase of water – called ‘superionic ice’ – by beaming X-rays through a diamond in the lab.  

Extreme conditions are necessary to produce superionic ice, sometimes referred to as ‘hot ice’, which adds to the other well-known phases of water – solid ice, liquid water and vapour gas. 

Superionic ice is a special crystalline form, half solid, half liquid – and it’s electrically conductive.  

Superionic ice is formed at extremely high temperatures and pressures at the centre of planets like Neptune and Uranus in the outer solar system. Pictured is a cutaway of Uranus

Superionic superionic ice forms at very high temperatures and pressures in the middle of planets such as Neptune, Uranus and Uranus. This is a slice of Uranus.

It was formed by extreme pressures and temperatures at the center of the planets Neptune in the outer Solar System. 

Knowing more about the different phases of H2O – of which there are several – could help find life on other planets, the scientists believe. 

Read more: Scientists create a mysterious phase of water – ‘supersonic ice’