Autumn leaves coated with frost

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Frost on autumn leaves

You can almost hear frost-coated autumn leaves crunching under your shoes as you walk through the woods. Though the calendar says it's still autumn, scenes like this highlight the colder temperatures as winter arrives in the Northern Hemisphere.

When water vapor in the air comes into contact with surfaces that are at or below the freezing point, the vapor quickly crystalizes into frost. It can make for charming scenery, or a reminder that you should have worn a heavier jacket.