frost

Frost is a white, crystalline deposit that forms on surfaces when the temperature is below freezing but the air is not saturated with water vapour.

Frost forms when water vapour in the air condenses on a surface that is below freezing. The water vapour molecules in the air collide with the surface and stick to it. As more and more water vapour molecules collide with the surface, they form a layer of ice that we call frost.

Frost can form on any surface that is below freezing, but it is most common on surfaces that are cold and smooth. This is because smooth surfaces have fewer imperfections for water vapour molecules to stick to.

Frost can be beautiful, but it can also be dangerous. For example, frost can make roads slippery and cause accidents.

The plants were killed by the frost.