Answer:
frost
Step-by-step explanation:
Frost is the deposition of water vapour from humid air or air containing water vapour on to a solid surface. Solid frost is formed when a surface, for example a leaf, is at a temperature lower than the freezing point of water and the surrounding air is humid.
In sub-freezing air, water vapour changes directly to ice without first becoming a liquid. This is how frost and hoar frost form on the ground or other surfaces. Another example is when frost forms on a leaf.