What are ice and frost?
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Key information
When it gets very cold, we often see frozen puddles or frost on the pavements and grass outside.
In this article you can find out:
- The difference between ice and frost
- How ice forms
- How frost forms
- What an ice sheet is
This resource is suitable for Weather topics for P2, P3, P4, P5, P6 and P7 (First and Second Level Curriculum for Excellence).
Watch this video to learn about ice and frost.
Wrap up warm as it looks cold outside! There’s frost on the cars and look - all the puddles have frozen into ice!
How does this happen?
Frost and ice form when the temperature falls below freezing – that’s less than 0 degrees Celsius.
For water to become a solid, like the frozen puddles in your street, it has to reach its freezing point. This is the point at which water cools to 0C,or even colder, and and becomes ice.
As well as low temperatures, ice also needs something to freeze onto. Cold surfaces, tiny bits of dirt, and other ice crystals are all ideal for this.
On very cold days during the winter, you may see icicles hanging from your roof. These are created by water droplets running down the roof and freezing to the surface when the temperature is 0°C or lower.
Overnight, more droplets flow down and freeze to the already frozen ice crystals, creating icicles. They continue to grow and get longer as more droplets freeze on the end of the icicle.
Frost is what we call the white ice crystals we see on a cold day. It is formed when water vapour lands on a surface, like the pavement or grass, which is already below freezing.
In the UK, we only usually see ice and frost in winter.
In some places, where the temperature is below freezing all the time, ice builds up in huge layers; covering large parts of the land for a long period of time. These are called ice sheets. The two biggest ice sheets on Earth cover most of Greenland and Antarctica - that’s a lot of ice!
How likely is ice to form where you are right now? Maybe you can check the temperature and find out!
How does ice form?
- Liquid water freezes and turns into a solid (ice) when the temperature is around 0°C or lower.
- Ice needs something to freeze on to like: cold surfaces, tiny pieces of dirt or other ice crystals.
How does frost form?
- There is in the air.
- Water vapour lands on a cold surface, like the pavement of grass, which is already at freezing point (0°C) or lower.
- The air is so cold that the water vapour condenses into liquid water droplets.
- The water droplets freeze and turn into tiny ice crystals, which we call frost.
Examples of ice and frost
Compare ice and frost in the UK to the ice sheets in Greenland and Antarctica.

Frozen puddle
When liquid water, like a puddle, reaches its freezing point (0°C or lower) it turns into ice. In this picture, the ripples in the water have frozen too.

Icicles
Icicles form when water droplets freeze as they flow downwards. More water droplets drip down and freeze on to the icicle. So the icicle gets bigger and longer.

Frost
Frost is what we call the tiny white ice crystals on surfaces outside, like leaves or the grass. Water vapour lands on a cold surface which is already below freezing (0°C or lower).

The Greenland ice sheet
An ice sheet is a large piece of ice that covers the land. The Greenland ice sheet covers about 1.7 million square kilometers of land. That's a lot of ice!

The Antarctic ice sheet
The Antarctic ice sheet is the largest piece of ice on Earth. Sadly, a lot of this ice is melting because of global warming. This means some animals are losing their homes and the sea levels are rising.
- ice - Frozen water.
- frost - Small white ice crystals on the ground or other surfaces when the temperature is below freezing.
- icicle - A hanging piece of ice formed when dripping water freezes. As water droplets flow downwards they freeze on the surface, so the icicle gets bigger and longer.
- Freezing point - The point at which water becomes a solid. This is usually at 0° Celsius or lower.
- Celsius - A unit of measurement used for temperature. 0° is the freezing point of water and 100° for the boiling point of water. It's also sometimes known as centigrade.
- ice sheets - Huge areas of ice that have built up and cover land over a long period of time. These can be found in Antarctica and Greenland, where it is extremely cold.